. 


THE  LIBRARY 

OF 

HOME  ECONOMICS 

A  COMPLETE  HOME-STUDY  COURSE 

ON    THE    NEW  PROFESSION    OF    HOME-MAKING  AND  ART  OF  RIGHT  LIVING; 

THE  PRACTICAL  APPLICATION  OF  THE  MOST  RECENT  ADVANCES 

IN  THE  ARTS  AND  SCIENCES  TO    HOME  AND    HEALTH 

PREPARED  BY  TEACHERS  OF 
RECOGNIZED  AUTHORITY 

FOR  HOME  MAKERS,  MOTHERS,  TEACHERS,  PHYSICIANS,  NURSES,    DIETITIANS, 

PROFESSIONAL  HOUSE   MANAGERS,  AND  ALL    INTERESTED 

IN  HOME,  HEALTH,  ECONOMY  AND  CHILDREN 

TWELVE  VOLUMES 

NEARLY  THREE  THOUSAND  PAGES,  ONE  THOUSAND  ILLUSTRATIONS 

TESTED  BY  USE  IN  CORRESPONDENCE  INSTRUCTION 

REVISED  AND    SUPPLEMENTED 


CHICAGO 

AMERICAN  SCHOOL  OF  HOME  ECONOMICS 
IC07 


^ 

I    UN!VERStT\ 


COPYRIGHT,  1907 

BY 
HOME  ECONOMICS  ASSOCIATION 

Entered  at  Stationers'  Hall,  London 
•  All  Rights  Reserved. 


DEDICATED  TO 

MRS.  HELEN  C.  KIMBERLY 

WHOSE  INTEREST  IN  THE  EDUCATION  OF  THE  HOME-MAKER 

AND  WHOSE  ENCOURAGEMENT  AND  ASSISTANCE 

HAVE  HELPED  TO  MAKE  POSSIBLE 

THE  LIBRARY  OF  HOME  ECONOMICS 


1 66746 


AUTHORS 


ISABEL  BEVIER,  Ph.  M. 

Professor  of  Household  Science,  University  of  Illinois.  Author  U.  S. 
Government  Bulletins,  "  Development  of  the  Home  Economics 
Movement  in  America,"  etc. 

ALICE  PELOUBET  NORTON,  M.  A. 

Assistant  Professor  of  Home  Economics,  School  of  Education,  Uni- 
versity of  Chicago  ;  Director  of  the  Chautauqua  School  of  Domestic 
Science. 

S.  MARIA  ELLIOTT 

Instructor  in  Home  Economics,  Simmons  College;  Formerly  Instruc- 
tor School  of  Housekeeping,  Boston. 

ANNA  BARROWS 

Director  Chautauqua  School  of  Cookery ;  Lecturer  Teachers'  College, 
Columbia  University,  and  Simmons  College;  formerly  Editor  "Ameri- 
can Kitchen  Magazine;"  Author  "  Home  Science  Cook  Book." 

ALFRED  CLEVELAND  COTTON,  A.  M.,  M.  D. 

Professor  Diseases  of  Children,  Rush  Medical  College.  University  of 
Chicago;  Visiting  Physician  Presbyterian  Hospital,  Chicago ;  Author 
of  "  Diseases  of  Children." 

BERTHA  M.  TERRILL,  A.  B. 

Professor  in  Home  Economics  in  Hartford  School  of  Pedagogy; 
Author  of  U.  S.  Government  Bulletins. 

KATE  HEINTZ  WATSON 

Formerly  Instructor  in  Domestic  Economy,  Lewis  Institute;  Lecturer 
University  of  Chicago. 

MARION  FOSTER  WASHBURNE 

Editor  "The  Mothers'  Magazine; "  Lecturer  Chicago  Froebel  Asso- 
ciation ;  Author  "  Everyday  Essays,"  "  Family  Secrets,"  etc. 

MARGARET  E.  DODD 

Graduate  Massachusetts  Institute  of  Technology  ;  Teacher  of  Science, 
Woodward  Institute. 

AMY  ELIZABETH  POPE 

With  the  Panama  Canal  Commission  ;  Formerly  Instructor  in  Practical 
and  Theoretical  Nursing,  Training  School  for  Nurses,  Presbyterian 
Hospital,  New  York  City. 

MAURICE  LE  BOSQUET,  S.  B. 

Director  American  School  of  Home  Economics ;  Member  American 
Public  Health  Association  and  American  Chemical  Society. 


CONTRIBUTORS  AND  EDITORS 

ELLEN  H.   RICHARDS 

Author  "  Cost  of  Food,"  "  Cost  of  Living,"  "  Cost  of  Shelter,"  "  Food 
Materials  and  Their  Adulteration,"  etc.,  etc.;  Chairman  Lake  Placid 
Conference  on  Home  Economics. 

MARY  HINMAN  ABEL 

Author  of  U.  S.  Government  Bulletins,  "  Practical  Sanitary  and  Econ- 
omic Cooking,"  "Safe  Food,"  etc. 

THOMAS  D.  WOOD,   M.  D. 

Professor  of  Physical  Education,  Columbia  University. 

H.  M.  LUFKIN,  M.  D. 

Professor  of  Physical  Diagnosis  and  Clinical  Medicine,  University  of 
Minnesota. 

OTTO  FOLIN,  Ph.  D. 

Special  Investigator,  McLean  Hospital,  Waverly,  Mass. 

T.  MITCHELL  PRUDDEN,  M.  D.,   LL.  D. 

Author  "Dust  and  Its  Dangers  "  "The  Story  of  the  Bacteria,"  "Drink- 
ing Water  and  Ice  Supplies,"  etc. 

FRANK  CHOUTEAU  BROWN 

Architect,  Boston,  Mass.;  Author  of  "The  Five  Orders  of  Architec- 
ture," "  Letters  and  Lettering." 

MRS.    MELVIL  DEWEY 

Secretary  Lake  Placid  Conference  on  Home  Economics. 

HELEN  LOUISE  JOHNSON 

Professor  of  Home  Economics,  James  Millikan  University,  Decatur. 

FRANK  W.  ALLIN,  M.  D. 

'  Instructor  Rush  Medical  College,  University  of  Chicago. 


MANAGING  EDITOR 

MAURICE  LE  BOSQUET,  S.  B. 

Director  American  School  of  Home  Economics. 


BOARD  OF  TRUSTEES 

OF  THE  AMERICAN  SCHOOL  OF  HOME  ECONOMICS 


MRS.  ARTHUR  COURTENAY  NEVILLE 

President  of  the  Board. 

MISS  MARIA  PARLOA 

Founder  of  the  first  Cooking  School  in  Boston;  Author  of  "Home 
Economics,"  "Young  Housekeeper,"  U.  S.  Government  Bulletins,  etc. 

MRS.  MARY  HINMAN  ABEL 

Co-worker  in  the  "New  England  Kitchen,"  and  the  "Rumford  Food 
Laboratory;"  Author  of  U.  S.  Government  Bulletins,  "  Practical 
Sanitary  and  Economic  Cooking,"  etc. 

MISS  ALICE  RAVENHILL 

Special  Commissioner  sent  by  the  British  Government  to  report  on  the 
Schools  of  Home  Economics  in  the  United  States;  Fellow  of  the 
Royal  Sanitary  Institute,  London. 

MRS.  ELLEN  M.  HENROTIN 

Honorary  President  General  Federation  of  Woman's  Clubs. 

MRS.  FREDERIC  W.  SCHOFF 

President  National  Congress  of  Mothers. 

MRS.  LINDA  HULL  LARNED 

Past  President  National  Household  Economics  Association ;  Author 
of  "  Hostess  of  To-day." 

MRS.  WALTER  McNAB  MILLER 

Chairman  of  the  Pure  Food  Committee  of  the  General  Federation  of 
Woman's  Clubs. 

MRS.  J.  A.  KIMBERLY 

Vice  President  of  National  Household  Economics  Association. 


MRS.  JOHN  HOODLESS 

Government  Superintend 
Ontario;  Founder  Ontari 
the  MacDonald  Institute. 


Government  Superintendent  of  Domestic  Science  for  the  province  of 
Ontario ;  Founder  Ontario  Normal  School  of  Domestic  Science,  now 


FOREWORD 


HE  Library  of  Home  Economics  is  the  result 
of  some  years'  experience  in  teaching  by  corre- 
spondence  what  may  be  termed  the  ' '  New  Pro- 
fession of  Home  Making,"  and  what  Mrs.  Ellen  H. 
Richards  has  called  the  fourth  ' '  R  "  in  education — Right 
Living. 

IJ  It  is  realized  that  the  business  of  housekeeping  has 
not  kept  pace  with  the  tremendous  advancement  in  other 
lines  of  human  endeavor,  that  the  wonderful  discoveries 
in  science  and  developments  in  the  arts  only  slowly  and 
partially  have  been  applied  to  the  problems  of  personal 
health  and  home  life. 

CJ  With  the  object  of  giving  home-makers  and  mothers, 
everywhere,  some  of  the  benefits  of  the  teaching  now 
offered  in  a  number  of  colleges  under  the  terms,  do- 
mestic science  and  home  economics,  the  correspondence 
courses  of  the  American  School  of  Home  Economics 
were  planned.  Special  lesson  papers  or  text  books  were 
necessary,  for  ordinary  text  books  are  not  adapted  to 
correspondence  instruction.  From  some  years  of  experi- 
ence in  correspondence  teaching  in  other  lines,  it  was 
known  that  the  lesson  books,  to  be  successful,  must  be 
simple,  concise,  non-technical,  and  above  all  sufficiently 
interesting  and  of  immediate  practical  value  to  hold  the 
attention  of  the  student  throughout  the  course. 
l|  The  aim  has  been,  not  to  teach  science  nor  to  teach 


theory,  as  such,  tmt  rather  the  best  scientific  practice 
with  sufficient  theory  to  show  the  reason  "why"  for  such 
practice ;  in  a  word,  to  give  as  much  real  help  and  prac- 
tical information  as  possible. 

l|  After  much  planning  and  consultation,  well  known 
teachers  were  invited  to  prepare  the  lesson  books  from 
the  standpoint  of  the  average  woman,  and  later  these 
same  teachers  have  given  or  supervised  the  correspond- 
ence instruction.  The  whole  course  is  so  planned  that 
each  series  of  lessons  fits  into  and  supplements  the  others, 
making  one  logical  whole,  without  duplication. 
€J  From  the  expressed  appreciation  of  nearly  two  thou- 
sand students,  the  results  sought  would  seem  to  have 
been  attained.  The  scientific  accuracy  and  scholarly  tone 
of  the  books  is  attested  by  their  use  as  text  books  in 
many  prominent  schools  and  colleges.  Although  prepared 
primarily  for  the  woman  in  the  home,  as  the  books  natur- 
ally embody  the  teaching  experience  of  their  authors, 
they  have  been  found  especially  valuable  to  teachers  and 
to  those  preparing  themselves  for  various  positions, 
fj  The  Library  contains  the  complete  series  of  lessons, 
including  test  questions,  which  the  active  members  of 
the  School  answer  in  writing  and  send  in,  as  a  written 
recitation,  for  the  correction  and  comment  of  the  teachers. 
This  correspondence  work  has  given  the  text  a  most  rig- 
orous and  effective  test  for  clearness  of  statement  and 
adaptability.  In  republishing  the  lessons  for  the  Library 
such  revisions  have  been  made  as  seemed  necessary  to 
clear  up  all  obscure  points  and  to  rectify  original  de- 
ficiencies. 

f|  In  addition,  much  supplementary  material  of  interest 


has  been  added  by  the  authors,  based  on  their  experience 
in  correspondence  instruction.  A  number  of  special  ar- 
ticles of  importance  are  also  included. 
(]  At  the  back  of  each  volume  will  be  found  a  program  or 
outline  for  supplemental  study,  making  virtually  an  ex- 
tension of  each  series  of  lessons.  These  are  arranged 
primarily  for  classes  taking  up  courses  with  the  School 
by  the  group  plan,  but  they  should  prove  of  equal 
value  to  the  individual  student  and  be  very  suggestive  to 
teachers.  The  reference  books  mentioned  and  the  small 
amount  of  apparatus  required  when  experiments  are  sug- 
gested are  loaned  to  members  of  the  School  when  not 
available  locally. 

€J  In  place  of  prefaces  to  the  volumes,  reproductions  are 
given  of  the  introductory  letters  of  the  instructors  which 
are  sent  to  students  when  each  new  subject  is  begun. 

l|  The  Library  is  published  to  give  the  members  of  the 
School  their  course  of  study  in  permanent  form,  with 
indexes  for  ready  reference,  and  in  binding  worthy  of  the 
contents.  It  will  also  serve  as  a  reading  course  for  asso- 
ciate members  of  the  School  and  will  be  available  as  a 
general  reference  work,  making  the  public  acquainted 
with  the  character  and  merit  of  the  correspondence 
courses  of  the  American  School  of  Home  Economics. 

C[  It  is  in  hope  that  it  may  serve  as  an  inspiration  and  an 
authoritative  guide  for  inexperienced  home-makers;  that 
it  may  open  up  a  new  world  of  interest  to  the  expen- 
enced  home-maker  and  give  added  meaning  and  impor- 
tance to  familiar  tasks;  that  it  may,  in  some  measure, 
increase  health  and  happiness,  that  the  Library  of  Home 
Economics  is  offered. 


VOLUMES 


I  THE  HOUSE:  ITS  PLAN,  DECORATION  AND  CARE 

II  HOUSEHOLD  BACTERIOLOGY 

III  HOUSEHOLD  HYGIENE 

IV  CHEMISTRY  OF  THE  HOUSEHOLD 
V  PRINCIPLES  OF  COOKERY 

VI  FOOD  AND  DIETETICS 

VII  HOUSEHOLD  MANAGEMENT 

VIII  PERSONAL  HYGIENE 

IX  HOME  CARE  OF  THE  SICK 

X  TEXTILES  AND  CLOTHING 

XI  STUDY  OF  CHILD  LIFE 

X  II  CARE  OF  CHILDREN 


LOUIS  PASTEUR.  FATHER  OF  BACTERIOLOGY 


Household  Bacteriology 


S.   MARIA  ELLIOTT 

INSTRUCTOR  IN  HOUSEHOLD  ECONOMICS 
SIMMONS  COLLEGE,  BOSTON 


CHICAGO 

AMERICAN  SCHOOL  OF  HOME  ECONOMICS 
1907 


s^>. 

OF  THE  ifc 

UNIVERSITY   1 

OF  / 

?N\^X 


COPYRIGHT,  1904,  BY 
AMERICAN  SCHOOL  OF  HOUSEHOLD  ECONOMICS 

COPYRIGHT,  IQ06,  BY 
HOME  ECONOMICS  ASSOCIATION 

Entered  at  Stationers  Hall,  London 
All  Rights  Reserved 


CONTENTS 


LETTER  TO  STUDENTS           .           .        .  .           .           .       y 

DUST            .          .          .          .          ..  .          ,             i 

DUST-GARDENS            .  ...        .         . .  .           .       '"  .       7 

DUST  PLANTS         .          .        ..  .       '••  '   •          •           15 

BACTERIA          .           «•/'.•».         .  .           .                 16 

MOLDS         .           /          •          .           .  .  '        ."           33 

YEASTS    .           ,                      .           .-  .           .           -39 

WORK  OF  BACTERIA        ,           .           .  .«^        •           47 

BUTTER  MAKING         ,        •  . .         .  .           .           -57 

CHEESE        .           .           .  .     v  ..          ,  .           .            58 

VINEGAR           .          .          .          .  ;          .          .60 

HARMFUL  DUST  PLANTS  .          ri           .  .           .           63 

PRESERVING  FOOD      .           ,           .'  .           .           .69 

DISEASE  GERMS     .           .           .           *  .           .           75 

RESISTANCE  OF  THE  BODY    .           ,  .           .           .      86 

SANITATION            .          .          .          .  .        • .           96 

HISTORY  OF  BACTERIOLOGY            .  .                      .    109 

SUMMARY     .           .           .           .           .  .*                   113 

EXTRACTS  FROM  THE  INSTRUCTOR'S  NOTE  BOOK          .    117 

SAFEGUARDS    OF    THE    BODY    AGAINST  DISEASE,    BY 

T.  MITCHELL  PRUDDEN             .  .           .           .127 

BIBLIOGRAPHY        .•          .         ...  .           .          153 

SUPPLEMENTAL  STUDY  OUTLINES    .  .           .           .    157 

INDEX          .          .          .          .          .•  «          .          163 


AMERICAN  SCHOOL.  OF  HOME  ECONOMICS 
CHICAOO 

January  i,  1907. 
My  dear  Madam t 

In  beginning  our  work  in  Household 
Bacteriology  together  I  should  .like  to  make  a  few 
suggestions  as  to  aims  and  methods  of  study. 

The  aims  to  be  reached  in  the  study  of  any 
science  are  at  least  two — a  knowledge  of  its  un- 
derlying principles  and  as  thorough  an  application 
of  those  principles  as  is  possible. 

For  the  principles  you  will  consult  the  lesson 
booklets.  Prom  them,  too,  you  will  gat  suggested 
applications,  but  the  subject  will  not  become  a 
part  of  yourself  until  you  recognize  new  applica- 
tions many  times  a  day.  It  is  said  that  no  person 
KNOWS  a  foreign  language  until  he  can  think  in 
that  language.  In  a  similar  way  you  will  want  to 
think  these  facts  into  your  life  and  work. 

Suggestions  for  study  have  already  been  given 
to  you.  I  hope  that  you  may  be  able  to  try  all  of 
the* experiments  suggested;  at  least  make  a  "dust 
garden"  as  described.  If  you  can  get  no  suitable 
dish,  a  regular  Petri  dish  may  be  obtained  through 
the  School  for  30  cents  and  a  tube  of  prepared 
"nutrient  gelatine" < for  20  cents.  The  dish  may 
be  returned.  Also,  I  hope  that  you  will  read  some 
of  the  books  recommended  in  the  bibliography. 

The  facts  of  bacteriology  underlie  so  firmly 
all  our  daily  living  that  there  is  no  need  to  go 
far  afield  for  illustrations.  But  a  thorough 
knowledge  of  the  science  can  be  gained  only  through 
laboratory  methods  and  with  a  microscope.  There- 
fore, I  hope  you  may  be  able  sometime  to  supple- 


ment  this  study  by  microscopic  work.  Perhaps 
through  the  aid  or  some  doctor  or  other  scientist 
you  may  be  able  now  to  get  a  peep  into  this  world 
of  the  unseen. 

If  these  lesions  point  out  dangers  of  which 
you  were  before  unconscious,  they  also  suggest 
ways  of  escape  from  those  dangers.  You  will  gain 
some  knowledge  of  the  causes  of  waste  and  disease 
If  this  leads  you  to  efforts  for  the  prevention 
and  removal  of  such  causes,  the  result  will  be 
those  healthful  conditions  which  make  the  most 
effectual  safeguard  against  the  attacks  pf  the 
few  micro-organisms  that  are  our  foes. 

I  hope  the  relations  between  hygiene  and  some 
of  the  daily  tasks  of  housekeeping  will  gain  a 
deeper  significance  in  your  mind;  and  this  ele- 
mentary study  may  result  not  only  in  pleasure  and 
profit  to  you,  but  also,  through  you,  in  better 
conditions  of  healthful  living  for  others. 

Sincerely  yours. 


Instructor 


FIG.  4.  PHOTOGRAPH  OF  A  DUST  GARDEN  AFTER  TWO  WEEKS 

GROWTH. 
Colonies  of  Mould  Marked  a;  Colonies  of  Bacteria  not  Marked. 


HOUSEHOLD  BACTERIOLOGY 


MOST  persons  now  know  that  mankind  is  greatly 
troubled  by  the  work  of  certain  minute  agents 
— variously  termed  germs,  bacteria,  micro-organ- 
isms. Few,  however,  realize  the  good  that  these 
forms  do,  or  understand  them  and  their  place  in  the 
world.  It  is  the  purpose  of  the  following  pages  to 
show  the  relations,  both  good  and  evil,  that  bacteria- 
and  other  micro-organisms  bear  to  the  household. 

DUST 

Most  housewives  look  upon  dust  as  an  undesirable  Prevalence 
thing  that  they  are  constantly  seeking  to  be  rid  of.  If 
dust  is  seen  on  the  piano  or  on  the  table  each  thinks 
she  will  be  considered  a  slack  housekeeper.  Perhaps 
some  are  not  troubled  by  the  presence  of  dust  that  does 
not  show.  Such  fight  the  enemy  vigorously  where  vis- 
ible, but  relax  effort  where  or  when  he  is  invisible. 
The  temptation  comes  to  hide  the  tell-tale  dust  by 
shutting  out  light. 

Few  persons  there  are  who  have  not  at  some  time 


HOUSEHOLD   BACTERIOLOGY. 


Dust-proof 

Room    or 

House 


Necessity 
of  Dust 


exclaimed,  "Where  does  all  the  dust  come  from  ?"  If 
a  house  be  thoroughly  cleaned  from  cellar  floor  to  attic 
ridge,  tightly  closed  for  months  or  years,  when  re- 
opened dust  will  be  found  in  great  quantities. 

This  is  true  even  in  the  country,  where  perhaps  a 
single  house,  removed  from  the  highway,  stands  sur- 
rounded by  grass  and  trees. 

The  "housekeeping"  of  ships  includes  dusting. 
The  officers'  quarters  of  the  government  ships  are 
dusted  regularly,  although  land  may  not  be  seen  for 
months  at  a  time. 

Scientists  have  tried  to  get  a  dust-proof  room  or 
house  in  which  to  carry  on  their  experiments.  This 
has  required  attention  to  location  and  site,  that  there 
should  be  no  jar  from  traffic  or  vibration  from  winds; 
a  careful  preparation  of  the  surrounding  soil;  numer- 
ous walls  separated  from  each  other  and  made  largely 
of  glass,  carefully  joined  and  hermetically  sealed.  The 
air  admitted  must  be  freed  from  its  dust ;  all  clothes 
ordinarily  worn  by  the  experimenter  must  be  ex- 
changed for  garments  especially  prepared  and  cared 
for,  before  he  enters  this  to-be-dustless  room.  Even 
then  all  surfaces  need  to  be  slightly  moist,  that  any 
stray  speck  of  dust  which  has  escaped  all  these  guards 
may  be  caught  and  held. 

Such  conditions  as  these  can  never  be  secured  in 
ordinary  life,  so  that  dust  will  probably  be  present  with 
us  always.  Indeed,  it  is  probable  that  were  all  dust 
exterminated,  life  also  would  become  extinct,  for  life 
in  its  most  efficient  forms  needs  light,  and  Tyndall 


DUST.  3 

proved  by  delicate  experiments  that  when  all  dust  was 
removed  from  the  track  of  a  beam  of  light,  there  was 
darkness.  So  before  the  command,  "Let  there  be 
light,"  the  dust  condition  of  light  must  have  been  pres- 
ent. Balloonists.  find  that  as  they  ascend  higher  the 
color  of  the  sky  deepens.  At  a  distance  of  some  miles 
the  sky  is  nearly  black,  there  is  so  little  dust  to  scatter 
the  rays  of  light.  If  the  stellar  spaces  are  dustless, 
they  must  be  black,  and  therefore  colorless.  The  mois- 
ture of  the  air  collects  about  the  dust-particles,  giving 
us  clouds,  and  with  them  all  the  glories  of  sunrise 
and  sunset.  Fogs.,  .too,  are  considered  to  be  masses 
of  "water-dust,"  and  ships  far  out  at  sea  have  had 
their  sails  colored  by  this  dust  while  sailing  through 
banks  of  fog. 

Astronomers  find  meteoric  dust  in  the  atmosphere.      Meteoric 

Dust 

When  this  falls  on  the  snow  and  ice  fields  of  the  Arctic 
regions  it  is  readily  recognized.  The  eruption  of  Kra- 
katoa  proved  that  volcanic  dust  is  disseminated  world- 
wide. 

An  old  writer  has  said :  "The  sun  discovers  atomes 
though  they  be  invisible  by  candle  light,  and  makes 
them  dance  naked  in  his  beams." 

Thus  dust,  just  common  e very-day  dust,  is  a  very      Source 

.    -J         of  Dust 

important  and  complex  substance,  which  promises 
much  of  interest  in  its  study.  Therefore,  again  we  ask 
where  does  it  come  from  and  of  what  is  it  made  ? 

When  a  March  wind  blows  over  a  sandy  road  or  a 
November  gale  sweeps  through  city  streets,  it  is  evi- 
dent that  a  large  part  of  the  dust  found  in  the  house 


HOUSEHOLD  BACTERIOLOGY. 


Ingredients 
of  Dust 


Movements 
of  Dust 


comes  through  open  doors  and  windows.  Few  win- 
dows and  doors  are  so  tightly  fitted  that  fine  dust  will 
not  sift  in  round  their  casings. 

Until  electricity  is  made  the  common  source  of  heat 
and  light,  there  will  be  much  dust  from  coal  and  wood, 
both  before  and  after  they  are  burned.  These  sources 
are  too  evident  to  need  more  than  a  mention.  It  is 
from  the  wear  and  tear  of  the  house  itself,  its  finish  and 
furnishings,  from  our  own  bodies  and  the  clothing  that 
covers  them,  that  the  larger  amount  of  dust  comes. 
From  these  we  have  bits  of  wood,  stone,  cotton,  hair, 
dead  cells  from  all  animal  bodies — a  mass  of  mineral, 
animal,  and  vegetable  matter  of  very  complex  compo- 
sition. 

Since  time  began,  everything  in  this  old  world  has 
thus  been  wearing  away  more  or  less  slowly,  adding 
bit  by  bit  to  similar  accumulations,  until  what  we 
know  as  soil  has  been  built  up — pure  mineral  soil  made 
from  the  debris  of  the  rocks ;  organic  soil  or  loam  from 
the  addition  to  this  mineral  soil  of  vegetable  and  ani- 
mal debris.  The  same  processes  are  continually  going 
on  all  about  us. 

The  dictionaries  recognize  this  process  when  they 
tell  us  that  dust  is  "Earth  or  other  matter  in  fine  dry 
particles  so  attenuated  that  they  can  be  raised  and  car- 
ried by  the  wind." 

Winds  then  are  the  responsible  agents  for  much  of 
the  dust  in  our  houses,  but  wind  is  simply  air  in  mo- 
tion. We  cannot  walk  across  the  floor,  make  a  bed, 
rock  comfortably  in  a  chair,  or  dance  a  jig  without 


DUST.  5 

making  some  wind  currents.  If  dust  is  present  in  this 
current,  it  will  be  stirred  up  to  settle  back,  where  it 
was  before,  or  to  be  blown  to  some  other  place.  The 
more  dust  or  the  stronger  the  wind,  the  surer  it  is  that 
the  dust  will  be  carried  along  with  the  current. 

But  why  should  the  housewife  spend  so  much  energy      why  Keep 

*  *\        Free  From 

and  time  in  trying  to  keep  her  house  free  from  dust?  Dust 
All  the  dust  elements  we  have  seen  so  far  are  not  likely 
to  do  her 'much  harm.  The  ashes  or  other  mineral  dust 
may  scratch  the  polished  table  or  the  brass  ornaments 
and  silverware,,  but  not  so  long  as  it  lies  quiet.  It  is 
the  moving  grain  of  sand,  not  the  still  one,  that 
scratches.  The  other  ingredients,  bits  of  dead  animal 
or  vegetable  matter,  may  be  disagreeable  to  think  of, 
but  they  are  of  the  same  stuff  as  ourselves,  our  clothes, 
our  furniture.  If  this  dead  matter  were  all  there  is 
to  dust,  no  one  would  ever  have  heard  of  the  science 
of  bacteriology. 

Many  of  the  daily  occurrences  in  the  home  give 
rise  to  questions  which  may  be  readily  answered  if  we 
will  but  turn  our  kitchens  into  laboratories  and  try 
some  simple  experiments. 

Perhaps  you  forgot  to  change  the  water  in  a  vase  of 
flowers  and  it  stayed  there  a  week.  How  did  it  smell 
when  you  poured  it  out  ?  How  did  the  stems  that  had 
been  in  the  dirty  water  feel? 

Possibly  when  you  left  home  for  a  week's  visit  last 
summer,  you  knew  the  ice  was  all  gone  from  the  refrig- 
erator, but  you  forgot  to  empty  the  pan  underneath. 


6  HOUSEHOLD  BACTERIOLOGY. 

What  did  you  find  on  your  return  ?    A  slimy  film  over 
the  surface  of  the  water,  did  you  not? 

Such  experiences  may  be  familiar  to  all.  A  few 
years  ago  these  changes  were  thought  to  be  due  to  the 
oxygen  of  the  air,  which  in  some  way,  under  certain 
conditions,  made  some  things  sour,  some  bitter,  and 
others  putrid. 

Leasread  "^n  ^e  ^ays  °^  our  grandmothers  much  of  the 
bread  was  made  with  leaven  like  that  used-  in  Bible 
times — a  mixture  of  flbur  and  water  exposed  to  the 
air  and  whatever  the  air  contained.  This  was  called 
"barm."  Such  bread  is  still  common  in  some  parts 
of  our  country,  and  known  as  "salt-rising  bread," 
and  the  barm  when  made  with  milk  is  called  "milk 
emptins." 

In  the  old  days  a  portion  of  the  leavened  mass 
was  kept  to  start  the  next  batch  of  bread.  Occa- 
sionally this  was  forgotten  or  it  spoiled,  then  the 
housewife  borrowed  from  her  neighbor,  as  when  the 
fire  on  the  hearth  was  out,  a  coal  was  borrowed. 
Sometimes  now  the  yeast  raised  sponge  becomes  slight- 
ly sour  before  it  is  ready  for  baking.  Why  ? 

Apple  or 'other  sauces  containing  sugar  ferment 
or  sour  and  the  housewife  scalds  them.  This  may 
make  them  as  palatable  as  when  freshly  stewed.  Yet 
they  often  turn  sour  again  and,  after  a  while,  scalding 
or  even  boiling  does  not  remove  the  sharp  or  sting- 
ing effect  upon  the  tongue. 

M.M°W          The  moist  bread  in  the  jar  is  found  specked  with 
mold ;    some   August   morning   the   sprinkled   clothes 


DUST    GARDENS.  7 

in  the  laundry  basket  are  mildewed;  the  "best  room," 
seldom  used  and  darkened  by  drawn  shades  and  tight- 
ly closed  blinds,  becomes  musty. 

What  do  all  these  things  mean,  or  have  they  any  re- 
lation to  each  other? 

We  will  now  see  if  we  can  answer  these  questions. 

Experiment  I.  Mix  a  little  yeast  with  some  sweet- 
ened water  and  let  it  stand  in  a  warm  place  where  the 
temperature  is  from  70°  to  75°  Fahr.  Put  a  few  table- 
spoonfuls  of  beef  broth  or  molasses  water  into  a  cup 
or  bottle  and  leave  it  uncovered  in  the  kitchen  where 
it  will  be  warm.  Watch  carefully  what  happens.  Be- 
fore long  bubbles  show  on  the  surface  of  the  sweetened 
water ;  perhaps  you  may  see  bubbles  rising  in  the  broth. 
If  left  long  enough  the  sweet  liquid  will  be  sour  and 
the  good  broth  smell  bad.  You  say  the  one  has  fer- 
mented, the  other  is  putrid.  What  has  made  the 
change?  You  did  not  add  anything  to  the  mixture; 
you  only  kept  it  warm  and  uncovered. 

DUST    GARDENS, 

Experiment  II.  From  any  dealer  in  laboratory  sup-, 
plies  or  through  the  doctor  or  druggist  get  a  Petri  dish 
or  plate.  This  is  simply  two  round  glass  dishes,  one- 
quarter  to  one-half  inch  in  depth,  one  just  large  enough 
to  fit  over  the  other  as  a  cover.  See  Fig.  i.  This  ex- 
periment can  be  made  without  the  Petri  dish,  although 
not  so  conveniently,  as  follows : 

Take  a  clear  glass  sauce  dish  or  a  finger  bowl.  Fig. 
2.  Cover  with  a  piece  of  smooth,  thin  glass  clear 


8  HOUSEHOLD   BACTERIOLOGY. 

enough  to  see  through  readily  and  large  enough 
to  entirely  and  tightly  cover  the  dish.  After 
washing  well,  place  both  together  in  a  pan  in  a  cool 
oven  and  gradually  raise  the  temperature  until  it  is  hot 
enough  to  bake  bread  or  to  yellow  a  piece  of  white 
paper  in  half  a  minute.  Let  them  bake  for  an  hour 
or  more.  Then  open  the  oven  and  place  the  pan 
where  the  dish  may  cool  slowly.  When  cold  take 
out,  without  removing  the  covering  plate,  and  put 
round  both  dish  and  plate  a  strong  rubber  band,  or  tie 
them  together  with  a  string. 

This  we  will  call  our  garden-plot.  But  a  garden  is 
of  little  use  without  something  growing  in  it,  and  for 
this  soil  is  required. 


FIG.  1.  PETRI  DISH  FOR  PLATE  CULTURES. 

soil  for  the         For  the  soil  take  the  following  recipe :     Chop  finely 

Dust-Gardens  *.  .  , 

one-quarter  pound  of  lean,  juicy  beef.  Mix  this  with 
one  cup  of  warm  water.  Heat  in  double  boiler,  stir- 
ring often  until  water  in  water  pan  has  boiled  fifteen 
mhrites.  Remove  inner  dish,  place  directly  over  the 
fire  and  allow  broth  to  boil  ten  or  fifteen  minutes. 
Clear  by  straining  through  two  or  more  thicknesses  of 


DUST    GARDENS.  9 

flannel  wet  in  cold  water.  Squeeze  the  meat  carefully 
to  get  out  all  its  juices  but  not  much  fat.  The  meat 
is  acid,  therefore,  add  from  one-eighth  to  one-quarter 
teaspoonful  of  bi-carbonate  of  soda.  Replace  the  water 
lost  through  evaporation. 

Moisten  three  heaping  tablespoonfuls  of  finely  di- 
vided  gelatine  in  a  very  little  cold  water  and  add  to 


FIG.  2.  SHALLOW  BOWL  COVERED  WITH  SHEET  OF  GLASS. 

the  boiling  hot  broth.  When  the  gelatine  is  dis- 
solved, strain  through  hot  flannel. 

Put  three  or  four  tablespoonfuls  of  the  broth  into 
each  of  several  small  bottles.  Plug  the  mouth  of 
each  with  a  close  wad  of  cotton  wool  or  tie  over  each 
a  thick  mat  of  the  same.  For  three  successive  days 
place  the  bottles  on  a  piece  of  folded  cloth  in  a  pan  of 
cold  water  and  boil  them  fifteen  minutes. 

Gelatine  melts  at  quite  a  low  temperature,  so  if  the 
dust  garden  is  prepared  in  summer  it  may  not  re- 
main solid.  If  kept  in  a  very  warm  place  in  the 
room  it  may  melt  at  any  time.  A  better  substance 
to  use  for  the  jelly  is  agar,  which  remains  solid  at  blood 
heat,  98.5°  Fahr.  This  may  be  found  in  some  cities 
at  the  druggists',  or  at  the  dealers  in  chemical  or  bac- 
teriological supplies.  It  solidifies  suddenly,  if  its  temper- 
ture  drops  below  a  certain  point,  and  as  it  is  rather 


10 


HOUSEHOLD   BACTERIOLOGY. 


Planting 
the   Garden 


difficult  to  prepare,  the  gelatine  is  more  favorable  for 
the  amateur's  use.* 

In  our  garden  we  want  only  certain  kinds  of  plants, 
and  we  want  to  know  just  where  they  come  from,  we, 


FIG.   3.     COLONIES  OF   DUST-PLANTS,   GROWN   ON  GELATINE. 
(After     Conn.f) 

therefore,  bake  the  dish  and  boil  the  jelly  until  sure 
that  nothing  in  either  is  alive. 

When  ready  to  plant  the  garden,  put  the  bottle  of 
jellied  beef  juice  into  a  dish  of  cold  water.  Heat  this 
until  the  jelly  is  melted  and  then  cool  slightly. 

*For  the  careful,  accurate  preparation  of  such  soil,  consult 
"Laboratory  Work  in  Bacteriology,"  Frederick  G.  Novy,  or 
any  other  manual  of  laboratory  practice  in  Bacteriology. 

A  Petri  dish  may  be  obtained  from  the  School  for  3oc 
and  a  bottle  of  agar  ready  for  use  for  24C  (in  stamps)  sent 
postpaid. 

tThe  "Story  of  Germ  Life,"  H.  W.  Conn;  D.  Appleton  & 
Co.,  Publishers. 


DUST    GARDENS.  n 

Remove  the  elastic  from  the  dish.  When  the 
tube  or  bottle  of  jelly  is  cool  enough  to  be  held  in 
the  hand,  remove  the  cotton  wool  plug  or  stopper, 
carefully  raise  the  cover  of  the  dish  on  one  side,  just 
enough  to  insert  the  mouth  of  the  bottle.  Pour  the 
melted  jelly  into  the  dish,  cover,  and  gently  turn  with 
a  circular  motion  until  the  jelly  is  spread  evenly  over 
the  bottom  of  the  dish.  Replace  the  elastic  and  let 
the  jelly  harden. 

The  garden  is  now  ready  for  planting.  To  do  this, 
all  that  is  necessary  is  to  remove  the  cover  and  leave 
the  dish  open  for  from  twenty  to  thirty  minutes.  If 
opened  in  a  very  dusty  place,  expose  only  ten  min- 
utes. Do  not  go  near  or  meddle  in  any  way.  At  the 
end  of  the  time  replace  the  cover  the  the  elastic  band. 
Let  the  dish  remain  in  a  warm  room  not  above  70°  F, 
and  watch  carefuly  for  whatever  happens. 

In  the  course  of  thirty-six  to  forty-eight  hours  or      Growth  of 

*  the  Garden 

longer,  minute  light-colored  specks  will  show  on  the 
surface  of  the  jelly.  These  will  be  seen  to  grow  lar- 
ger, to  become  of  different  colors— pink,  yellow, 
orange,  green,  blue,  possibly  a  deep  red. 

Some  spots  will  be  shiny,  smooth,  and  round ;  oth- 
ers branched  like  mosses  or  seaweeds;  others  with 
white  rims  and  dark  centers,  showing  a  pile  like 
velvet,  and,  when  seen  through  the  sides  of  the  dish, 
they  may  suggest  minute  pins  with  ball  heads.  Fig.  3. 
All  of  these  forms  may  not  show  themselves,  but  in 
most  cases  there  will  be  seen  the  shiny,  smooth  spots, 


UNIVERSITY 


of 


12  HOUSEHOLD   BACTERIOLOGY. 

and  the  hairy  or  velvety  ones.  Look  at  the  garden 
through  a  magnifying  glass,  if  possible ;  watch  every 
change ;  write  down  an  accurate  and  full  account  as 
to  time,  appearance,  conditions  of  temperature,  light, 
etc.  Then  change  the  conditions.  Put  the  dust- 
garden  into  the  refrigerator,  shut  it  into  a  box,  etc. 
See  how  the  colonies  are  affected  by  each  new  condi- 
tion or  by  any  two  combined. 

If  a  compound  miscroscope  can  be  used,  touch  the 
point  of  a  needle  to  one  of  the  spots  and  place  the 
speck  of  matter  taken  up  on  a  clean  glass  slide.  Put 
on  a  drop  of  cool  boiled  water,  and  over  this  a 
cover  glass ;  examine  carefully  for  shape  and  motion ; 
draw  what  is  seen.  In  this  way  examine  the  differ- 
ent colonies  to  see  if  the  forms  in  all  are  of  the  same 
shape. 

Putrefaction  Let  the  dust  garden  grow  for  a  week  or  more,  then 
gently  raise  the  cover,  smelling  of  the  contents,  and 
as  this  is  done,  if  the  growth  is  sufficiently  far  ad- 
vanced, there  will  be  sensible  proof  that  dust-plants 
may  cause  putrefaction.  The  next  time  you  are 
tempted  to  leave  a  piece  of  meat  exposed,  remember 
the  dust-garden,  and  cover  the  meat  with  a  cloth  to 
keep  out  dust. 

Figures  4  and  5  are  photographs  of  such  dust-gar- 
dens after  more  than  two  weeks'  growth.  The  prin- 
cipal colonies  of  molds  are  marked  a,  and  the  those 
marked  b  are  colonies  of  bacteria.  In  Fig.  5  the  row 
of  colonies  marked  b  shows  well  how  thickly  they 


FIG.  5.     A  DUST  GARDEN. 

(a)      Colonies  of  Mould.  (b)      Colonies  of  Bacteria, 

(b')     Colonies  of  Bacteria  on  a  Thread. 


DUST  GARDENS.  13 

sometimes  crowd  together.     Probably  these  were  all 
attached  to  some  tiny  fibre  of  wood  or  cloth. 

The  soil  or  "nutriment  gelatine"  in  our  experiments  Kindg  of 
had  beef  juice  in  it ;  you  will  ask  if  any  other  soil 
would*  do.  The  gardener  knows  that  his  pinks  will 
grow  better  in  one  place  and  his  ferns  in  another  be- 
cause each  requires  or  likes,  we  may  say,  a  particular 
kind  of  food  which  that  soil  contains. 

In  the  laboratory  numerous  soils  or  nutrient  media 
are  used — milk,  potato,  beer,  blood-serum,  etc. 

A  moment's  thought  will-  show  that  all  the  food 
substances  which  we  like  best  are  subject  to  changes 
which  in  general  we  designate  as  "spoiling."  Some 
grow  bitter,  some  sour,  some  odorous,  some  rancid. 
In  a  few  cases  this  result  is  due  to  processes  brought 
about  by  mere  chemical  changes — that  is,  without  the 
intervention  of  any  living  agent  or  ferment;  but  in 
most  cases  where  food  spoils,  it  is  due  to  the  growth 
on  or  in  the  substance  itself  of  the  little  plants,  which 
have  been  carried  to  it  through  ordinary  dust. 

The  milk  in  the  pantry  is  found  to  be  sour.  When 
it  was  secreted  by  the  milk  gland  in  the  cow's  body  it  ofUMUk 
was  sweet  and  pure.  It  passed  down  into  the  milk 
duct  in  its  passage  outward,  and  here  perhaps  it  met 
a  few  of  the  dust-plants  which  had  passed  into  the 
mouth  of  the  duct  from  the  outside.  Hundreds,  no 
doubt,  fell  into  the  pail  from  the  dusty  air  of  the  stall 
the  cow's  hairy  coat,  the  milkman's  clothes,  or  hands, 
or  hair,  even  from  the  pail  itself,  for  all  are  more 


14  HOUSEHOLD  BACTERIOLOGY. 

or  less  dusty.  Among  these  hundreds  of  forms  are 
some  that  like  the  sugar  of  the  milk  as  food.  While 
feeding  upon  this,  they  change  a  part  of  it  into  acid- 
lactic  acid.  When  this  acid  reaches  a  certain  amount, 
it  coagulates  the  casein  of  the  milk. 

production  The  cleaner  the  milk,  the  fewer  of  these  lactic  aciti 
producing  plants  will  be  present  and  the  longer  the 
milk  will  keep  sweet.  Cold  retards  their  growth. 
Milk  should  then  be  cooled  as  quickly  as  possible 
after  being  drawn  from  the  cow,  and  should  be  kept 
in  a  cold  place  all  times. 

Milk  is  a  most  favorable  culture  ground  for  bac- 
teria because  it  has  some  of  all  classes  of  food  ele- 
ments, being  what  is  known  as  a  perfect  food.  Its 
opaqueness  hides  much  of  the  solid  dirt  which  not 
only  seeds  it  with  bacteria  but  adds  certain  soluble 
matters.  Too  often  the  dirty  character  of  the  milk  is 
known  only  by  sight  of  the  actual  dirt  at  the  bottom 
of  the  empty  glass. 

The  possibilities  in  the  way  of  clean  milk,  which 
means  safe  milk,  were  forcibly  illustrated  by  exhibits 
from  some  American  "model  dairies"  at  the  Paris  Ex- 
position in  1904.  Milk  and  cream  in  a  perfectly  fresh 
condition  were  shown  after  a  journey  of  ten  days;  the 
only  treatment  being  extreme  cleanliness  in  milking,  sta- 
ble, receptable,  etc.,  and  cold.  A  glass  of  ordinary,  un- 
clean milk  contains  millions  of  bacteria,  which  al- 
though harmless  to  a  vigorous  adult  are  the  cause,  di- 
rect or  indirect,  of  the  death  of  thousands  of  young 
children  annually. 


DUST  PLANTS.  15 

DUST  PLANTS 

We  have  seen  from  the  dust-garden  that  dust  does 
contain  living  plants  which,  when  they  find  food  in  a 
moist,  warm  place,  will  grow  and  multiply. 

They  were  not  seen  when  they  settled  out  of  the 
dust  on  the  jelly,  and  not  until  they  had  reproduced 


Fig.    6.     (a)     One  Colony   of   Bacilli   or   Rod-Shaped    Bacteria    as   Seen   in 

"Dust   Garden."     Highly    Magnified. 

(b)     Eight   Bacteria   from  the  Colony,   Magnified  Much  More. 
(After  Prudden.) 

themselves  many  times,  so  that  a  "colony"  was  formed, 
were  we  able  to  see  that  anything  had  been  planted 
in  the  dust  garden.  But  each  colony  or  spot  shows 
where  a  single  plant  dropped  on  the  gelatine ;  the  spot 
becomes  visible  only  after  it  contains  thousands  of  in- 
dividuals, which  are  kept  close  together  by  the  gelatine. 


Colony    of 
Dust  Plants 


16  HOUSEHOLD  BACTERIOLOGY. 

of          All  of  these  dust-plants  have  to  be  studied  under 

Dust  Plants 

the  microscope  and  are  therefore  called  micro-organ- 
isms. Microbe  —  a  name  given  by  Louis  Pasteur— 
which  from  its  derivation  would  include  all,  has 
come  gradually  to  be  applied  to  one  class,  the  bac- 
teria. Still  a  third  word,  germ,  which  really  means 
the  beginning,  or  that  first  living  cell  which  produces 
a  more  complex  form,  is  becoming  restricted  to  the 
micro-organisms  that  cause  disease,  as  the  germ  of 
tuberculosis,  the  germ  of  typhoid  fever,  etc.  All 
-~  these  names  may  apply  to  micro- 

£&       scopic  animal  forms  as  well.     Strict- 
ly speaking,  all  dust-plants  are  germs, 
all  are  microbes,  all  are  micro-organ- 
b    isms. 

The     ''garden"      will     show     two 
kinds    of    plants    and    sometimes    a 
c     third,   although   this   is   not   so   com- 
mon  in   house   dust.      We   will   now 
see  what  these  three  kinds  of  plants 

Fig.     7.       Typical     ai"C>     tw°     °f     which     WC     "^     exPect 

<a?orS>cci°f   oractBan    to    fincl    in    ail    Bouses    at    an      time. 
' 


Forms,   (b)   Bacilli,    f^e    third,    wild    yeast,    would    very 

or    Rod-shaped 

Si™8'  or  'spiral   likely    be   caugnt   if   we   planted   our 
Form's.  dust  garden  under  the  apple  trees  in 

summer  time. 

BACTERIA 

Let  us  find  out  first  what  the  plants  are  like  which 
make  the  smooth,  glossy,  shiny  colonies,  whether  round 
or  radiate.  These  are  the  bacteria,  and  each  colony 


BACTERIA. 


has   come    from    the   reproduction    of   one    parent — a 
bacterium.    Fig.  6. 

Under  the  microscope  these  bacteria  show  three 
principal  shapes.  Fig.  7.  One  like  a  short,  round 
stick  or  rod,  is  called  a  bacillus  and  bacilli  for  the 
plural.  Fig.  7b.  Another  is  ball-shaped,  called  coccus 
or  cocci  for  the  plural  (the  third  c  sounding  like  s). 
Fig.  73.  A  third  form  which  resembles  one  turn  or 
more  of  a  screw  is  called  a  spirillum 
or  spirilla  for  the  plural.  Fig.  7c. 

These  typical  forms  may  shade 
into  each  other.  The  bacilli  may  be 
long  or  short,  with  pointed,  blunt, 
Dr  spirilla  for  the  plural.  Fig.  7c. 
short  and  plump  as  to  closely  re- 
semble a  coccus.  Fig.  8.  The  spi- 
ral forms  may  curve  very  little  or 
have  decided  and  numerous  twists. 
Fig.  9. 

Bacteriologists  do  not  always  agree 
as  to  which  class  a  newly  found  indi- 
vidual should  belong,  and  to  the  housewife  it  makes 
no  difference. 

The  bacteria  are  so  simple  in  structure  and  so  diffi- 
cult to  study  that  there  is  little  to  describe.  Each 
consists  of  a  single  cell,  so  far  as  is  known.  This 
seems  to  have  a  denser  portion  on  the  outside,  which 
forms  a  cell  wall  and  may  be  cellulose  as  in  the  higher 
plants. 

This  simple  cell  of  protoplasm  or  "foundation  stuff" 


Fig.  8.  Bacilli  or 
Rod-shaped  Bacte- 
ria. 


Shape    of 
Bacteria 


Excretions 
*i    Bacteria 


i8 


HOUSEHOLD  BACTERIOLOGY. 


is  endowned  with  all  the  characteristics  of  living  matter 
anywhere. 

All  living  things  whether  plant  or  animal  take 
food  in  some  way.  All,  too,  having  taken  food, 
change  it  over  into  their  own  substance  and  give  out 


FIG.    9.     DIFFERENT    FORMS    OF    SPIRILLA. 

some  of  the  results  of  these  changes  as  waste  prod- 
ucts in  the  form  of  gases,  liquids,  or  solids. 

Bacteria  are  no  exception  to  this  universal  rule. 
Their  products  are  either  gases  or  liquids  and  these, 
dissolved  in  blood  or  other  liquids,  bring  about  vari- 
ous changes,  the  results  of  which  may  be  either  de- 
sirable or  undesirable,  according  to  the  nature  of  the 
bacterium,  the  amount  of  the  excretion,  or  other  con- 
ditions under  which  the  changes  are  wrought. 

The  processes  of  bacterial  growth  in  the  human 
body  and  in  food  substances  are  similar. 


BACTERIA.  19 

The  excretions  of  the  bacteria  in  milk,  fish,  etc,, 
may  produce  changes  which,  very  apparently,  ren- 
der them  unfit  for  food,  or  the  changes  may  not  be 
apparent.  If  food  containing  these  excretions  be 
eaten,  or  if  the  bacteria  grow  in  the  body  itself,  the 
excretions  may  bring  about  abnormal  conditions  more 
or  less  severe,  but  all  may  be  called  disease. 

Like  the  mag- 
gots in  cheese  or 
the  clothes  moth 
larva,  the  bacteria  fvg  -„„  _. 

1    A     K          ffl    ffi  3 

live  surrounded  by  ffl   {j^ 
their    food    supply 

and  they  have  only  A 

to  take,  digest,  and     FIG-   10>    A  BACILLUS  DIVIDING  INTO 
absorb  it  as  need-  TWO  GENERATIONS. 

ed.  Like  these  animal  forms,  they  feed  upon  com- 
plex organized  food  which  has  been  previously  pre- 
pared by  other  plants  or  animals.  In  this  they  differ  • 
from  most  plants  which  must  manufacture  their  food 
out  of  the  mineral  and  other  inorganic  substances  in 
air,  water,  or  soil.  However,  some  species  can  do 
this  although  they  have  not  the  green  coloring  mat- 
ter or  chlorophyll  cells  which  in  the  higher  plants  are 
the  food  factories. 

Because  of  this  power  of  living  on  inorganic  sub- 
stances,  which  no  known  animal  possesses,  the  sci- 
entists have  decided  that  these  micro-organisms  must 
be  called  plants  rather  than  animals. 

Bacteria  have  no  leaves,   roots,   stems,  or.  any   or- 


2O 


HOUSEHOLD  BACTERIOLOGY. 


Food   of 
Bacteria 


Fig,    11.     Different   Forms   of   Bacilli. 

(a)  Simple,     detached     forms. 

(b)  Chains    of    united    bacilli. 


gans  like  higher  plants.     They  are   simply  transpar- 
ent bits  of  jelly-like  protoplasm. 

Bacteria  in  general  like  the  same  kinds  of  food  that 
man  likes,  although  they  do  not  requi're  the  variety 
in  diet  which  to  civilized  man  seems  necessary 

Some  flourish  best  in 
meat  juices,  others  in 
milk,  some  in  starchy 
foods,  others  in  su- 
gary solutions,  while 
still  others  enjoy  best 
the  fats. 

They  also  show,  like 
man,  a  surprising  faculty  of  adaptation.  If  unable  to 
get  their  favorite  food,  many  will  grow  on  whatever  is 
at  hand.  Any  organic  substance  which  is  not  absolutely 
dry  may  become  food  for  some  species  of  dust-plants. 
Dust-plants  will  not  leave  the  moist  surfaces  upon 
which  they  fall,  but  where  such  surfaces  become  dry, 
then  the  plants  are  ready  to  be  blown  into  the  air  by 
winds  or  carried  along  on  anything  which  touches 
them. 

Ordinarily  dust  particles  are  probably  never  so  dry 
that  the  bacteria  or  other  micro-organisms  clinging  to 
them  are  killed. 

All  bacteria  reproduce  by  division  of  the  parent 
into  halves,  which  process  is  called  fission.  Fig.  10. 
Sometimes  these  daughter  cells  remain  attached  even 
after  they  themselves  have  divided  into  two.  A 


BACTERIA. 


21 


chain  of  cells  results  so  that  what  looks  under  the 
microscope  like  one  individual  may  be  three  or  more 
generations.  Fig.  n. 

The  ball  forms  divide  in  the  same  way  along  a  di- 
ameter, jf  Some,  however,  divide  in  more  than  one  di- 


FIG.    12.     REPRODUCTION    OF    COCCI    BY    FISSION. 
Division    into    two.  (c)     Division    into    four, 

(d) 


(a) 

(b)  Chains  of  cocci. 


A  sheet  of  four  cocci. 


rection,  so  that  the  colony  of  daughter  cells  may 
touch  at  one  side  only,  like  closely  strung  beads,  or 
on  two  sides,  making  a  sheet  or  film  of  cells,  or  they 
may  become  piled  upon  each  other  like  a  cube  of 
marbles.  Fig.  12. 


22  HOUSEHOLD  BACTERIOLOGY. 

The  spiral  forms  also  may  remain  in  one  colony  or 
break  up  into  single  cells  after  division. 

Sometimes  they 
unite  their  bodies 
by  a  gelatinous 
film  to  form  a 
slime  over  the  sur- 
face of  whatever 
FIG.  is.  ZOOGLOEA  OR  THE  they  are  growing 

FILM-FORMING     BACTERIA. 

upon,    as    seen    on 

the  walls  of  the  waste  pipe  of  the  refrigerator  or  on 
the  surface  of  the  water  in  the  pan.  This  is  known 
as  a  zoogloea  form.  Fig.  13. 

Rapidity  The  rapidity  with  which  they  reproduce  depends 
largely  upon  the  food  supply,  the  warmth  and  moist- 
ure— that  is,  whether  the  conditions  of  life  and 
growth  are  favorable. 

In  this  prolific  reproduction  lies  their  great  power 
for  harm  or  benefit  to  the  world. 

In  some  species,  under  favorable  conditions,  a  new 
generation  is  born  oftener  than  every  half  hour.  If 
this  rate  were  continued  for  a  day,  one  bacterium 
might  become  ancestor  of  over  sixteen  million  de- 
scendants. Some  interested  observer  has  calculated 
that  in  two  days  the  billions  thus  born  would  fill  a 
pint  measure  and  weigh  a  pound,  while  in  another 
twenty-four  hours  their  weight  would  equal  eight 
thousand  tons. 

These  numbers,  however,  are  of  no  practical  im- 


Of 


BACTERIA.  2 

portance,  for  long  before  such  a  population  was 
reached  the  food  supply  would  be  gone  or  the  parent 
forms  would  be  killed  by  their  own  excretions.  Here, 
as  in  the  animal  world,  if  the  wastes  of  living  accu- 
mulate, death  results.  Yet  wherever  conditions  of 
moisture,  warmth,  and  food  remain  favorable  they 
will  multiply  with  almost  infinite  rapidity. 

Botanically  the  bacteria  belong  to  the  fungi,  and 
because  they  reproduce  by  fission  or  breaking  into 
two,  they  are  called  Schizomycetes  or  Fission  Fungi. 

A  string  of  sausages,  often  seen  hanging  in  the  win- 
dows of  a  market,  is  a  fair  representation,  except  in 
size,  of  a  chain  colony  of  bacteria. 

Take  a  piece  of  white  rubber  tubing,  ten  to  twelve 
inches  long  and  from  one-half  to  one  inch  in  diam- 
eter. Tie  it  tightly  at  one  end  with  waxed  thread. 
Fill  this  about  three-quarters  full  of  water  and  tie 
the  second  end  so  that  no  water  may  escape.  From 
thread  to  thread  will  represent  very  well  a  bacillus. 

Divide  this  in  the  middle  by  a  rubber  band  and  two 
generations  are  represented  or  a  chain  colony  of  two 
individuals.  The  same  method  may  be  continued  to 
show  the  future  reproduction  processes. 

Their  minute  size  would  seem  to  indicate  insig- 
nificance, but  they  make  up  in  energy,  in  the  work 
done,  and  in  numbers,  for  all  that  is  lacking  in  size. 
Not  one  is  ever  visible  to  the  naked  eye,  while  some 
can  be  seen  only  with  great  difficulty  by  the .  skilled 
observer  and  under  the  most  powerful  microscope. 

They  are  so  small  that  little  idea  of  their  size  can 


Bacteria 
Are    Classed 
as   Fungi 


Size     of 
Bacteria 


24 


HOUSEHOLD  BACTERIOLOGY. 


toRoiygen 


be  obtained  by  actual  measurement,  only  by  compari- 
son. Fig.  14  represents  the  largest  bacterium  known 
magnified  six  hundred  diameters.  One  twenty-five 
thousandth  of  an  inch  is  not  an  uncommon  length  for 
a  bacterium. 

Yet,  small  as  they  are,  they  are  heavier  than  air, 
and  therefore  settle  out  of  it  when 
it  is  still. 

It  is  estimated  that  in  the  space 
occupied  by  a  grain  of  sugar  there 
might  be  packed  six  hundred  mil- 
lions and  each  bacterium  be  com- 
fortable. Compared  with  the  bac- 
teria  which  may  lodge  there,  the 
wrinkles  in  the  skin  of  our  hands 
are  like  ditches  six  or  eight  feet 
deep.  No  wonder  that  it  is  diffi- 
cult to  dislodge  them  by  any  ordi- 
nary washing.  The  surgeon  has  to  resort  to  a  strong 
soap,  vigorous  brushing,  and  the  use  of  numerous 
bacterial  poisons  in  addition  to  the  ordinary  washing, 
before  he  is  sure  that  these  valleys  are  not  rich  in  the 
tiny  plants  that  might  bring  suffering  or  death  to  his 
patient. 

Most  of  the  bacteria  require  oxygen  to  breathe,  as 
we  do,  but  some  can  live  without  air.  Some  will  ac- 
commodate themselves  to  any  condition.  Preferring 
much  or  little  oxygen,  they  will,  however,  grow  under 
the  opposite  condition,  if  they  must. 


4.       Bacmus 
(a   a^dgab)eriuimiivid- 
<cuaid  d>    TWO  mm- 
vVS8'intoeaChaivedsl: 


BACTERIA.  25 

Of  course,  the  disease  germs  which  grow  in  the  in- 
terior of  our  bodies  flourish  best  under  conditions  of 
darkness  and  lessened  air  supply.  Out-of-door  •  life, 
then,  is  a  preventive  measure,  and  next  to  this  is  a 


Disease 

and 

Darkness 


FIG.    15.     SUNSHINE   AS   A   DISINFECTANT.      (After   Lefar.) 
Under   the   letters   of   black -paper   there   was  growth;    In  the  remainder 
of   the   plate   the   sunlight   killed   the    bacteria. 

generous  supply  of  sunlight  and  fresh  air  inside  our 
houses. 

Experiments   have    shown   that   the   disease   germs 


HOUSEHOLD  BACTERIOLOGY. 


Effect    of 
Sunlight 


Power   of 
Movement 


live  much  longer  when  grown  in  a  cellar  than  when 
cultivated  in  the  light  rooms  of  a  house. 

All  disease  germs,  so  far  as  known,  are  killed  by 
direct  sunlight.  This  was  proved  some  years  ago 
by  planting  a  Petri  dish  with  typhoid  fever  germs. 
Half  of  the  dish  was  covered  with  black  paper,  while 
the  uncovered  half  was  exposed  to  direct  sunlight. 
On  the  sunlighted  half  no  growth  appeared,  while 
the  other  half  showed  many  colonies.  A  similar  ex- 
periment is  illustrated  by  Fig.  15. 

In  this  experiment  the  letters  of  the  name  "Ty- 
phus" were  cut  out  of  black  paper  and  placed  on  the 
under  side  of  the  cover  of  a  Petri '  dish  which  had 
been  planted  with  bacteria.  The  dish  was  exposed 
to  sunlight  for  an  hour,  and  a  half  and  then  left  in  a 
dark  room  for  twenty-four  hours.  When  the  paper 
letters  were  removed,  the  space  covered  by  them  was 
found  thickly  studded  with  the  minute  colonies  of 
bacteria.  The  rest  of  the  plate  showed  no  appearance 
of  bacterial  life. 

Some  bacteria,  like  most  of  the  higher  plants,  re- 
main stationary,  having  no  power  of  motion,  while 
others  move  by  slow  or  jerky,  worm-like  contrac- 
tions. Still  others  are  moved  about  by  whip-like  ex- 
tensions of  their  bodies,  called  flagella  or  cilia.  Some 
have  only  one  whip  at  one  end  of  the  body,  others 
one  or  a  cluster  at  each  end,  while  others  have  them 
reaching  out  from  all  parts.  Fig.  16. 

Some  bacteriologists  place  all  the  forms  which  have 


BACTERIA.  27 

flagella    in    one    species — Bacillus,    and    all    withoul 
flagella  in  another  species— B  acterium. 

When  for  any  reason  there  comes,  a  period  of  hard 
times  in  the  life  history  of  the  bacteria,  such  as  cold, 
dryness,  or  lack  of  food,  some  bacteria  have  the 


BACTERIA  WITH  FLAGELLA. 

(a)  A   flagellum   at   one   end. 

(b)  A   flagellum    at   each   end. 

(c,    d.   and  e)     Tufts  of   flagella   in   different  positions. 
(After  Conn.) 

power  of  contracting  their  bodies  into  smaller  space, 
possibly  drawing  it  all  into  one  end  or  from  the  mid- 
dle into  each  end.  Fig.  17.  This  is  called  the  spore 
stage.  These  spores  can  weather  great  extremes  of. 
famine  or  cold  or  resist  the  action  of  strong  chem- 
icals. Some  can  be  frozen,  others  boiled  and  still  re- 
tain life.  When  good  times  return  in  the  form  of 


Spores 


HOUSEHOLD  BACTERIOLOGY. 


Resistance 
of  Spores 


Dust    Plants 

in  the 

Refrigerator 


moisture,  warmth,  or  more  food,  the  resting,  resist- 
ant spore  starts  into  growth  again  and  continues  its 
life  as  before. 

The  species  that  do  not  form  spores  are  much 
more  easily  killed.  Those  that  form  spores  readily, 
being  difficult  to  kill,  are  more  likely  to  cause  dis- 
ease or  destruction  of  property.  Fortunately  for  us, 
most  of  the  disease  or  "pathogenic"  germs  do  not 
form  spores  readily,  if  at  all.  It  is  these  spores  that 
make  necessary  the  repeated  "scalding"  by  which  the 
housewife  tries  to  save  the  food  which  she  finds  spoil- 
ing. 

The  lowest  temperature  known  will  not  kill  some 
bacteria,  while  some  varieties  in  the  spore  state  will 
resist  the  temperature  of  boiling  water.  Indeed  the 
heating  sometimes  seems  to  favor  their  changing  into 
the  active  state. 

Dust  readily  finds  access  to  the  ice  box  or  the  refrig- 
erator, even  if  the  ice  is  thoroughly  cleaned  before  it  is 
put  in.  The  dust-plants  will  grow  on  any  bits  of  food 
carelessly  dropped  and  by  their  gaseous  products  may 
taint  the  meat,  milk,  and  other  foods.  The  escape  pipe 
of  a  refrigerator  needs  to  be  often  and  carefully 
cleaned  throughout  its  entire  length,  else  it  will  be 
covered  with  a  slimy  mass  of  bacterial  erowth.  Many 
of  the  bacteria  found  here  are  the  germs  of  putrefac- 
tion. 

This  pipe  may  be  cleaned  with  a  swab  of  cloth  or 
sponge  tightly  wrapped  around  a  long  stick,  rat- 
tan or  whalebone,  with  a  small,  long-handled  brush, 


BACTERIA. 


29 


or  if  the  pipe  is  too  difficult  of  access  for  these 
methods,  a  boiling  hot  solution  of  washing  soda  may 
be  poured  down  once  a  week,  or  when  the  ice  box  is 
empty. 

The  pan  under  the  refrigerator  should  be  scrubbed 
carefully  with  hot  soapsuds  or  scalded  with  the  wash- 


FIG.   17.     VARIOUS  SPORE   BEARING  BACTERIA, 
(a)     Spores   Escaping   from   Ruptured   End.      (After  Conn.) 

ing  soda,  that  -no  slime  may  appear.  The  escape 
pipe,  too,  should  be  opened  to  the  air  and  in  a  place 
where  the  air  will  be  pure. 

The  housewife  who  allows  her  refrigerator  pipe  to 
empty  directly  into  a  hole  in  the  cellar  floor,  un- 
derneath which  is  a  slimy  mass  of  muddy  filth,  need 
not  be  surprised  that  milk  and  butter  do  not  "keep 
well." 


30  HOUSEHOLD  BACTERIOLOGY. 

Boiling  The  greatest  argument  in  favor  of  boiling  clothes 
in  the  laundry  is  based  on  the  bacteriological  reason. 
Body  clothes,  bedding,  towels  and  handkerchiefs  may 
all  become  soiled  with  discharges  of  the  mucous  mem- 
branes of  the  body  or  from  some  wound  or  pus 
formation.  In  most  of  these  discharges  there  is  sure 
to  be  bacteria.  Soap  has  a  slight  disinfecting  power, 
but  the  boiling  is  far  more  efficacious.  Scalding  or 
the  pouring  of  boiling  water  over  the  clothes  is  not 
sufficient  for  disinfection,  for  only  the  top  surface  is 
subjected  to  the  high  degree  of  heat  necessary  to 
kill  the  germs.  •  Soap  or  other  alkali,  boiling,  fresh 
air,  and  sunshine  are  a  sanitary  quartet  whose  work 
results  in  sterilization — that  is,  in  death  to  the  germs. 

Natural         The  natural  home  of  the  bacteria  is  the  soil.    Here 

Home   of 

Bacteria  they  are  most  numerous  because  here  they  have  their 
greatest  field  of  work  laid  out  for  them,  which  is  to 
change  any  dead  vegetable  and  animal  matter  that  may 
be  present  into  inorganic  substances  which  can  do  no 
harm  to  life. 

When  winds  blow  over  the  soil  they  raise  the  dry 
dust  particles  laden  with  bacteria  into  the  air;  rain 
washes  .millions  of  them  from  the  air  and  soil  into 
the  brooks  and  rivers;  therefore,  all  surface  waters 
are  seeded  with  bacteria. 

From  the  soil  they  may  be  directly  brought  into  the 
house  on  shoes,  or  clothes,  or  hands ;  indirectly  through 
dusty  air. 

The  cleaning  of  shoes  on  a  mat,  brush,  or  scraper 


BACTERIA. 


outside  the  front  door  is  a  habit  to  which  all  chil- 
dren should  be  trained.  Adults  should  think  what  it 
means  to  bring  street  filth  into  the  dry,  warm  house. 
If  all  coats,  dresses,  etc.,  worn  on  the 'street  could  be 
brushed  out  of  doors  still  another  fruitful  source  of 
dangerous  dust  would  be  avoided.  House  air  is 
found  to  contain  thousands  of  bacteria,  where  out-of- 
door  air  may  have  only  hundreds,  because  moist  sur- 
faces catch  and  hold  them.  Sunlight  and  large 
amounts  of  fresh  air  tend  to  kill  them.  The  house  has 
less  fresh  air,  less  sunshine,  and  it  is  filled  more  or 
less  with  dry,  rough  furnishings,  which  add  to  the  dust 
and  all  tend  to  hinder  its  removal  and  to  lessen  the 
chances  of  disinfection. 

In  the  laboratory  bacteria  are  studied  in  many 
ways.  Under  the  microscope  is  noted  their  shape  and 
size;  what  kind,  and  the  rapidity  of  motion,  if  any; 
how  they  tend  to  arrange  themselves  upon  division; 
whether  spores  are  formed  or  not. 

From  plate  and  other  cultures  can  be  seen  the 
shape  and  color  of  the  colony;  whether  they  grow 
best  on  the  surface,  in  much  air,  or  below  the  surface 
where  air  is  excluded;  whether  the  temperature  of 
the  room  is  more  favorable  than  that  of  the  incubator, 
which  is  much  higher  and  represents  more  nearly 
the  conditions  inside  of  our  bodies. 

Some  of  the  bacteria  secrete  an  acid  which  lique- 
fies the  gelatine  on  which  they  may  be  growing.  This 
acidity  can  be  detected  by  litmus  paper.  Some  pro- 
duce a  gas  when  grown  in  -a  sugary  solution,  others 


Laboratory 
Study 


Secretions 


32  HOUSEHOLD  BACTERIOLOGY. 

cause  putrefaction.  Each  of  these  differences  means 
much  to  the  trained  observer,  for  from  .such  results 
has  been  and  must  be  gathered  our  knowledge  of 
their  probable  behavior  outside  of  the  laboratory, 
importance  In  the  bacteriological  laboratory  has  been  found 
Bacteriology  ou*  facts  which  in  the  commercial  life  of  the  world 
mean  millions  of  dollars;  there,  too,  have  been  started 
experiments  which  have  led  to  incalculable  saving  of 
human  suffering  and  life,  through  sanitation,  pre- 
ventive medicine,  and  surgery. 

Here  we  see  how  the  little  things  of  life  have  con- 
founded the  mighty  and  how  "the  science  of  the 
infinitely  small,"  by  which  some  one  has  defined  bac- 
teriology, "has  become  the  infinitely  important." 


DUST  PLANTS. 


33 


MOLDS 


Another  micro-organism  which  is  seldom  absent 
from  house  dust,  either  as  the  plant  cell  itself  or  its 
spore,  is  mold.  This  in  our  dust  garden  formed  the 
:olonies  with  dark  centers  and  a  velvety  pile.  Molds 


FIG.   18.     A  GROWTH  OF  MOLD. 
Mycelium,    Hyphae   and   Spore-cases.      (After    Jorgensen.) 

consist  of  vegetative  portions  which  grow  out  in  long 
threads,  and  these  by  budding  and  branching  unite 
to  form  a  network  over  the  substance  they  are  using 
as  food.  Fig.  18. 

From  this  network  or  mycelium  grow  out  cells  called 
hyhae  set  apart  for  special  wprk — that  of  bearing  the 
reproductive  portion — the  heads,  or  stalked  clubs. 
Inside  these  heads  or  from  their  outer  surface 


Growth    of 
Mold 


Reproduction 


34 


HOUSEHOLD  BACTERIOLOGY. 


FIG.     19.     MOLDS    SHOWING    A    MYCELIUM    BRANCH,     (m.) 

(a)  With   ripe   spores    (s). 

(b)  A    spore-bearing    stalk    with    spores    just    forming. 

(c)  Spores   have    fallen.      (After  Jorgensen.) 


MOLDS. 


35 


grow  the  spores  which  are  to  reproduce  the  species. 
Figs.  19  and  20.  Each  head  produces  thousands  of 
dust-like  spores.  Fig.  21.  This  is  the 
common  method  of  reproduction  in  the 
molds,  although  some,  like  the  bacteria  be- 
low them  in  the  scale  of  nature,  break  the 
parent  cell  into  segments,  while  others  send 
off  buds  like  yeast.  These  buds  form  di- 
rectly the  second  generation. 

When  the  invisible  spore  falls  upon  a 
moist,  warm  surface,  i't  immediately  begins 
to  grow  by  sending  out  the  mycelium 
branches,  which  will  then  proceed  as  before 
to  develop  more  spore-bearing  cells. 

Sometimes  these  mycelium  cells  pene- 
trate into  the  food  substance,  very  much 
like  the  roots  of  the  higher  plants. 

One  of  the  effects  of  mold  growth  is  seen  in  the  soft- 
ening of  cellulose  in  fruits,  vegetables,  etc.  This  makes 
their  decomposition  by  the  bacteria  more  speedy  and 
thorough.  Out-of-doors  this  action  is  of  great  use  in 
the  economy  of  Nature,  but  inside  our  houses  the  pres- 
ence and  growth  of  molds  should  be  guarded  against 
in  every  way. 

In  general,  molds  will  grow  with  less  moisture  than 
bacteria,  and  some  of  them  flourish  in  the  light.  They 
increase  rapidly  after  rainstorms  and  are  much  less 
affected  than  the  bacteria  by  winds.  They  need  or- 
ganized food,  as  we  well  know  from  the  places  where 
we  find  them  growing — bread,  meat,  leather,  sugary 
liquids,  or  even  in  vinegar. 


FIG.  20. 


OF  THE 


36  HOUSEHOLD  BACTERIOLOGY. 

W°Moids  In  &eneral  tney  form  fewer  desirable  products 
than  do  the  bacteria,  although  this  may  be  consid- 
ered a  matter  of  taste.  Those  who  like  Limburger 
and  Brie  cheese;  the  Chinese  "soy,"  which  is  made 
from  a  kind  of  bean  on  which  mold  has  grown;  the 
Japanese  "sake"  or  rice  wine,  which  has  been  fer- 
mented by  molds — these  persons  certainly  would 
claim  that  molds  were  as  valuable  in  the  production 


Q   Q 

e 

FIG.    21.     DIFFERENT    STAGES    IN    THE    DEVELOPMENT    OF   MOLD. 

(a,   b,    c   and   d)     Growth   of   the  spore-eases. 

(d')     The    spore-cases   open. 

(e)      Spores.      (After   Jorgensen.) 

of  flavor  as  the  bacteria  are  in  butter  and  ordinary 
cheese. 

Just  what  their  action  is  upon  digestion  is  not  defi- 
nitely understood.     It  is  thought  that  many  of  them 
cause  a   lax  condition   in   the   bowels,   possibly   diar- 
rhoea. 
Disease         They   are   found   to   cause   various   diseased   condi- 

from    Molds 

tions  of  the  skin — Ringworm,  Thrush,  and  Moth. 
The  moth  patches,  often  called  Liver  spots,  because 
believed  to  be  due  to  an  inactive  liver,  are  found  to  be 
caused  by  mold  spores  which  have  gained  access  to 


MOLDS.  37 

the  body  tissues  through  some  break  in  the  skin. 
Fairly  strong  acetic  acid — 40  per  cent — is  one  of  the 
best  remedies  for  moth. 

They  sometimes  penetrate  quite  deeply  into  the  tis- 
sues, causing  irritation,  inflammation,  or  sores  very 
difficult  to  heal  because  there  can  be  no  healing  until 
the  plant  is  killed. 

Food  fully  penetrated  by  mold  growth  would  bet- 
ter be  destroyed.  When  the  growth  occurs .  only  on 
the  surface,  as  on  jelly,  olives,  pickles,  etc.,  the  mat  of 
cells  protects  the  food  beneath  and  most  of  it  is  un- 
harmed. Such  foods,  however,  are  often  softened 
by  the  products  of  mold  and  bacterial  growth,  when 
no  sign  of  mold  appears  on  the  fruit  itself.  If  eaten, 
various  intestinal  disorders  are  liable  to  occur. 

Moist  cloth  furnishes  favorable  soil  for  mold  when  Mildew 
warm  and  not  open  to  fresh  air.  The  folded  gar- 
ments laid  away  gather  moisture;  dust  containing 
mold  spores  is  usually  present  on  them,  and  in  time, 
soon  or  late,  the  garments  grow  musty  even  if  there 
be  no  visible  mold.  Mustiness  is  the  proof  of  mold, 
and  mold  the  proof  of  dampness  and  dust.  We  call  the 
mold  growing  on  the  cloth  mildew,  but  called  by  either 
name  it  is  the  same  dust-plant.  The  plant  must  be 
killed  to  stop  its  growth.  If  it  has  grown  only  on 
the  surface  of  the  fibre,  the  stain  may  sometimes  be 
removed  without  serious  injury.  If  it  is  of  long 
growth  or  has  penetrated  the  fibre,  a  hole  will  result, 
because  of  the  weakened  or  actually  destroyed  fibre. 

So  far  as  the  healthful  house  is  concerned,  there 


38  HOUSEHOLD  BACTERIOLOGY. 

need  be  no  separation  in  the  mind  between  molds  and 
bacteria,  because  the  occurrence  and  conditions  of 
growth  of  both  are  practically  alike.  So  far  as  is 
known,  there  are  no  molds  that  cause  such  serious  and 
fatal  diseases  as  some  of  those  caused  by  bacteria. 

Because  molds  are  lighter  than  the  bacteria,  it 
takes  much  longer  for  them  to  settle.  The  air, 
then,  is  likely  to  contain  molds  even  where  it  has 
been  quiet  so  long  that  the  bacteria  have  all  settled. 
This  gives  the  housewife  another  reason  for  the 
economy  of  keeping  the  air  of  her  kitchen,  pantries, 
or  any  place  where  food  is-  prepared  or  stored,  as  free 
from  dust  and  as  dry  as  possible. 

Moldy  In  old  houses  it  is  sometimes  impossible  to  keep 
food  in  certain  closets  or  cupboards;  The  woodwork 
or  plaster  and  therefore  the  air  is  so  charged  with 
mold  spores  that  one  damp  day  or  the  presence  of 
warm,  moist  food  alone  will  cause  them  to  spring 
into  growth.  Such  places  should  be  often  white- 
washed and  painted  or  disinfected. 

The  spores  of  molds  are  often  very  beautiful  in  color 
when  seen  in  mass,  and  under  the  microscope  they 
show  exquisite  forms  and  delicate  ornament.  These 
factors,  as  well  as  the  substances  upon  which  the  mold 
grows,  are  used  as  means  of  distinguishing  species. 

The  botany  of  molds  is  to  many  as  interesting  a 
study  as  that  of  the  higher  plants.  Only  a  micro- 
scope can  bring  out  the  beauties  of  this  class  of  dust- 
plants,  which  from  the  standpoint  of  economy  and 
health  the  housewife  can  view  with  disfavor  second 


• 


YEASTS.  39 


only  to  that  she  bears  for  some  of  the  bacteria.  So 
many  more  of  the  bacteria  are  friends  rather  than 
foes  that  it  may  be  more  just  to  place  mold  as  her 
chief  enemy. 

YEAST 
The  third  variety  of  plants  found  in  dust  is  yeast,      size  and 

»  •  '  Structure 

These  are  not  usually  so  numerous  as  either  the  bac-  of  Yeast 
teria  or  the  molds,  although  about  apple  trees  in  the 
country  wild  yeasts  are  common.  Like  a  bacterium, 
the  yeast  plant  is  a  single  microscopic  cell  of  pro- 
toplasm enclosed  by  the  cell  wall.  •  It  is  round  or  oval 
in  shape  and  often  one  two-thousandth  of  an  inch  in 
diameter.  Fig.  22.  It  is  therefore  quite  a  giant  com- 
pared with  the  smallest  bacterium. 

If  a  drop  of  tepid  water  in  which  bread  yeast  has 
been  dissolved  be  carefully  watched  under  the  micro- 
scope, the  changes  shown  in  Figs.  23  and  24  may  be 
seen.  One  cell  will  be  seen  to  swell  a  little  at  one 
part.  This  bud  or  daughter  cell  will  bulge  out  more 
and  more  from  the  parent  and  may  even  produce  one 
or  more  generations  from  itself  before  it  breaks  away. 
This  "budding"  is  the  method  of  reproduction  common 
to  yeast  plants  of  which  there  are  many  varieties. 

Some  species,  however,  reproduce  by  spores  very  Spores 
much  like  the  molds.  Such  yeast  cells  will  be  seen 
to  divide  within  the  cell  wall  into  two  or  four  rounded 
bodies  which  in  growing  soon  rupture  the  parent 
cell  and  escape.  Fig.  25.  Each  of  these  liberated 
spores  forms  a  new  plant  which  may  produce  buds. 


Requirements 
for   Growth 


40 


HOUSEHOLD  BACTERIOLOGY. 


Thus  the  generations  are  continued  and  the  individuals 
multiplied. 

Yeast  requires  food,  oxygen,  warmth,  and  moisture. 
Sugary  substances  are  especially  liked  by  the  yeast 
which  is  used  to  make  bread.  This  is  a  specially  cul- 
tivated form  of  brewer's  yeast.  Yeast  directly  from 


FIG.    22.     TYPICAL    FORMS    AND    APPEARANCE    OF    BREWERS' 
YEAST.      (After    Sedgwick    and    Wilson.) 


Products 
of    Growth 


the  breweries  is  often  used  for  breadmaking.  It 
is  while  feeding  upon  these  sugary  solutions  that 
the  tiny  plants  bring  about  the  chemical  changes  by 
which  alcohol  and  the  gas,  carbon  dioxide,  are  pro- 
duced. The  gas  puffs  up  the  dough  and  makes  pos- 


YEASTS.  41 

sible  the  raised  bread,  or  the  "election  cake"  like  that 
of  our  grandmother's  time;  it  also  produces  the 
"froth"  and  "sparkle"  of  the  "home-made  spruce  beer" 
as  well  as  that  of  the  large  breweries. 

Yeast  plants  grow  best  from  70°  F.  to  90°  F.    They 


FIG.  23.     A  YEAST  GARDEN. 


do  not  work  well  under  70°  F.  and  are  killed  when  in 
a  moist  state  by  the  temperature  of  130°-! 50°  F.  No 
wonder  the  bread  will  not  rise  when  the  cook  pours 
boiling  or  even  hot  water  on  the  cake  of  yeast !  Dead 
plants  cannot  work  any  more  than  dead  animals.  No 


Favorable 
Temperature 


Cold  and 
Yeasts 


42  HOUSEHOLD  BACTERIOLOGY. 

working  by  the  yeast  means  no  possible  raising  of  the 
dough  by  the  gas.  Sometimes  the  dried  yeast  cake 
has  been  carelessly  prepared  in  this  respect  and  the 
yeast  plants  are  nearly  all  dead. 

The  yeast  plants  can  endure  cold  better  than  heat. 


FIG.    24.     YEAST    PLANTS    IN    VARIOUS    STAGES    OF    BUDDING    OB 
REPRODUCTION.      (After    Sedgwick    and    Wilson.) 


Experiment 
with  Yeasts 


It  hinders  their  work  but  does  not  quickly  kill  them. 
To  show  the  favorable  or  unfavorable  tempera- 
ture for  the  growth  of  yeast  plants,  take  one-half 
cup  each  of  boiling,  lukewarm  and  ice-cold  water. 
Add  to  each  one  tablespoonful  of  molasses  and  one- 


YEASTS.  43 

sixteenth  of  a  cake  of  compressed  yeast.  Put  each 
portion  into  a  clear  glass  bottle  or  tumbler  and  place 
all  three  in  a  warm  place,  about  75°  or  80°  F.,  for  an 
hour  or  two.  Watch  carefully  for  the  first  sign  of 
bubbles  which  show  that  gas  is  forming.  Note  in 
which  glass  the  larger  amount  of  gas  is  found. 


a 

FIG.  26.     YEAST  GENERATING  CARBON  DIOXIDE. 

(a)  Tube   filled   with   molasses   and   water. 

(b)  Carbon    dioxide    collecting    in    top    of    tube. 

Fill  a  test  tube  or  thin,  clear  glass  vial  with  a 
mixture  of  molasses  and  tepid  water.  Add  a  little 
yeast  and  invert  the  vial  in  a  dish  which  also  con- 
tains molasses  and  water.  Fasten  the  vial  so  that  it 
will  remain  standing,  closed,  in  the  dish  for  a  day  or 
more.  Fig.  26,  a  and  b. 


44 


HOUSEHOLD  BACTERIOLOGY. 


The    Gas 
Produced 


Compressed 
Yeast 


The  gas  will  be  formed,  replacing  the  water  in  the 
vial.  If  a  burning  match  is  held  in  the  mouth  of  the 
tube  as  it  is  removed  from  the  water,  the  flame  will 
be  extinguished.  This  indicates  that  the  vial  con- 
tains the  gas  carbon  dioxide ;  or  a  teaspoonful  of 
clear  lime  water  may  be  poured  into  the  vial  and 
shaken  about  in  it.  The  carbon  dioxide  present  will 
turn  the  lime  water  milky  from  the  insoluble  car- 
bonate of  lime  (calcium)  formed. 

Compressed  yeast  is  sim- 
ply a.  mass  of  yeast  plants 
mixed  with  some  form  of 
starch  and  pressed  into 
cakes.  A  two-cent  cake  is 
said  to- contain  over  half  a 
billion  yeast  plants. 

As  these  cakes  are  made 
for  a  special  purpose  they 
should  contain  only  one  species  of  yeast.  They  do, 
however,  contain  bacteria  and  if  the  dough  is  allowed 
to  rise  too  long  or  at  too  high  a  temperature  they 
grow  and  produce  an  acid  which  makes  the  bread 
sour;  so  that  sour  bread  results  from  the  growth  of 
bacteria  and  not  from  the  yeast.  When  pure  yeast  is 
used  and  all  conditions  of  cleanliness  are  carefully 
looked  after  no  sour  bread  results.  A  dusty  kitchen 
or  unclean  utensils  may  increase  the  danger  from  bac- 
terial growth.  If  the  bread  be  made  with  milk,  this 
should  be  scalded  to  kill  the  bacteria  always  present. 
As  we  have  seen,  milk  is  rich  in  dust-plants,  especially 


FIG.  25.  A  YEAST  CELL  CON- 
TAINING FOUR  SPORES. 


YEASTS.  45 

bacteria,  and  the  dirtier  the  barn,  the  cows,  the  pails, 
or  the  clothes  and  hands  of  the  milker,  the  more  bac- 
teria the  milk  contains. 

The  baking  of  bread  should  kill  both  the  bacteria 
and  yeasts,  as  well  as  molds,  if  any  are  there.  But 
it  will  not  do  this  unless  continued  for  a  long  time, 
because  the  inside  of  the  loaf  will  not  be  raised  to  a 
temperature  sufficiently  high.  The  moisture  in  the  in- 
terior prevents  a  temperature  much  higher  than  212° 
and  it  may  remain  far  be- 
low this. 

In  the  laboratory  bread 
has  been  made  from  the 
yeast  plants  found  alive  in 
the  center  of  a  slack-baked 
loaf.  The  bread  should  re- 
main in  the  oven  until  well 

,  Fig.    27.     Bacteria   Found   in   the 

done,  then  when   removed  "Eyes"  of  potatoes, 

it  should  be  cooled  as  rap- 
idly as  possible,  that  all  growth  of  yeast  or  bacteria 
may  be  stopped. 

The  custom  of  some  housewives  of  wrapping  the 
hot  loaf  in  thick  cloth  that  the  steam  may  soften  the 
crust  is  entirely  wrong  from  a  bacteriological  stand- 
point. 

During  the  baking  the  alcohol  and  carbon  dioxide 
are  both  driven  off. 

Coarse  breads,   those  containing  much  bran   espe-      coarse 
cially,  need  thorough  baking,  because  on  the  outside  of     Meals 
the  grains  are  often  certain  bacteria,  the  spores  of 
which  are  very  resistant  to  even  high  heat. 


46  HOUSEHOLD  BACTERIOLOGY. 

Some  of  these  are  found  in  large  numbers  in  the 
soil  which  clings  to  underground  vegetables,  especially 
in  the  "eyes"  of  potatoes.  No  wonder  a  vegetable 
brush  is  necessary  to  clean  away  these  clinging  arms! 
Fig.  27. 


TEST  QUESTIONS 

The  following  questions  constitute  the  "written  reci- 
tation" which  the  regular  members  of  the  A.  S.  H.  E. 
answer  in  writing  and  send  in  for  the  correction  and 
comment  of  the  instructor.  They  are  intended  to 
emphasize  and  fix  in  the  memory  the  most  important 
points  in  the  lesson. 


HOUSEHOLD  BACTERIOLOGY 

PART   I. 


Read  Carefully.  Place  your  name  and  address  on  the  first 
sheet  of  the  test.  Use  a  light  grade  of  paper,  write  on  one 
side  of  the  sheet  only,  and  leave  space  between  answers. 
Use  your  own  words,  so  that  your  instructor  may  know  that 
you  understand  the  subject.  Read  the  lesson  book  a  num- 
ber of  times  before  attempting  to  answer  the  questions. 
Answer  every  question  fully. 


1.  What  are  bacteria?     Describe  them. 

2.  What   other   microscopic    forms    are    found   in 

dust  and  what  are  favorable  conditions  for  the 
growth  of  these  dust-plants  ? 

3.  Where  are  bacteria  most  numerous  and  what  is 

their  chief  work  in  the  world  ? 

4.  In  what  ways  are  bacteria  helpful  to  man  and 

in  what  way  do  they  injure  him  or  his  pos- 
sessions ? 

5.  Why  should   food  eaten  raw  or  unskinned  be 

thoroughly  cleaned? 

6.  What  sanitary  end  is  attained  by  cooking  food  ? 

7.  Why  are  oranges  and  bananas  safer  fruits  than 

grapes  or  peaches  bought  from  a  street  ven- 
der? 

8.  How  can  scalding  apple  or  other  sauce  prevent 

its  spoiling,  and  why  scald  it  more  than  once? 


HOUSEHOLD  BACTERIOLOGY. 

9.     What  common  diseases  in  man  are  attributed  to 
molds  ? 

10.  What  is  mildew,  and  under  what  conditions  in 

the  house  would  it  be  likely  to  appear? 

11.  Are  molds  ever  helpful  to  man? 

12.  From  the   health  standpoint,   what   clothes  are 

most  likely  to  need  boiling  ? 

13.  Why   shpuld   milk   receptacles     be    thoroughly 

scalded  or  sunned? 

14.  When  a  can  of  blueberries  ferments  or  "spoils," 

what  does  it  mean? 

15.  Why  are  bacteria  considered  to  be  plants? 

16.  How  do  bacteria  reproduce  themselves  and  what 

food  do  they  prefer? 

17.  What  is   the  typical   mode  of  reproduction   in 

yeast?     In  mold? 

1 8.  What  is  the  chief  work  of  the  yeast  plant? 

19.  Give  a  report  of  your  dust-garden  experiment. 

20.  What  do  you  consider  the  most  important  ways 

in   which  you   have    applied    the    knowledge 
gained  from  this  lesson  ? 

21.  Are  there  parts  of  this  lesson  that  are  not  clear? 

Have  you  some  questions  ? 

Note.— After  completing  the  test  sign  your  full  name. 


CELLS  OF  CLOVER  TUBERCULE,  SHOWING  BACTERIA 
HIGHLY  MAGNIFIED 


UNIVERSITY 

OF 


HOUSEHOLD   BACTERIOLOGY 

PART  II. 


WORK  OF  BACTERIA 

When  bacterial  life  first  appeared  upon  the  earth 
may  never  be  known,  but  that  it  existed  thousands  of 
years  before  man  made  its  acquaintance  is  surely  true. 
Indeed,  it  was  within  the  last  quarter  of  the  nine- 
teenth century  that  the  knowledge  of  bacteria  became 
of  value  or  was  reduced  to  a  science.  The  problems  of 
bacteriology  are  now  being  solved  very  rapidly.  What 
future  generations  may  add,  who  can  tell  ? 

Although  bacteriology  is  the  youngest  of  all  the 
sciences,  it  occupies  a  very  important  place  among 
them  because  of  its  intimate  connection  with  disease, 
with  sanitation  or  the  prevention  of  disease;  with 
successful'  agriculture,  and  with  the  manufacture  of 
many  products. 

In  the  eyes  of  the  law  every  person  is  considered     useful 
innocent  until  proved  guilty.     It  may  be  well  for  us     Bacteri* 
to  look  at  the  beneficent  role  which  bacteria  play  in 
the   world,   that   we   may   the   more   justly   consider 
their  harmful  work.     We  can  hardly  believe  that  the 
most  numerous  forms  of  life  were  intended  to  work 
only  harm  to  man. 

47 


HOUSEHOLD   BACTERIOLOGY 


Bacteria  as 
Scavengers 


Fig.  28.  Bacteria 
which  Help  in 
Plant  Food. 


in     Soil 
Making 


As  soon  as  an  organism  begins  to  live  it  begins  to 
die;  that  is,  certain  cells  or  parts  of  cells  die  and  are 
perhaps  cast  off  from  the  rest  that  the  whole  may 
not  be  injured.  Animals  and 
plants  die  and  become  dan- 
gerous to  the  welfare  of 
other  animal  life,  especial- 
ly to  man.  The  wastes  of 
life,  of  his  own  life  even,  are 
man's  greatest  menace. 
.  Here  come  to  his  aid  these  microscopic  scavengers, 
the  bacteria.  No  doubt  the  molds  assist  in  the  process 
but  the  balance  of  the  work  is  done  by  the  bacteria  pres- 
ent in  such  infinite  numbers  everywhere  on  the  earth 
where  organic  matter  exists. 
Through  their  agency  all 
dead  animal  and  vegetable 
substances — that  is,  all  or- 
ganic matter — are  changed  in- 
to inorganic  matter,  into  the 
chemical  compounds  or  ele- 
ments out  of  which  they  were 
originally  constructed,  and 
which  are  harmless  or  helpful 
to  the  life  of  the  world. 

A  tree  falls  in  the  woods;  an  elephant  or  a  bird 
dies  in  the  jungle;  just  then  and  there  the  millions  of 
bacteria  in  the  soil  and  the  air  are  ready  to  seize  upon 
the  dead  bodies,  and  in  time  all  the  animal  and  vege- 


Fig.  29.  Bacteria  Found  in 
Soil  and  on  the  Roots  of 
Clover,  Peas  and  Other 
Leguminous  Plants. 


WORK  OF  BACTERIA 


49 


tables  tissues  are  changed  into  gases  which  dissipate  in- 
to the  air  or  reunite  into 
compounds  that  form  a 
part  of  the  soil.  These 
then  become  once  more 
food  for  plant  life,  and 
this,  in  turn,  for  the  sus- 
tenance of.  animals. 

Bacteria  are  the  agents 
of  decay  by  which  all  or- 
ganic materials  are  re- 
turned to  the  soil  or  the 
air.  Thereby  life  is  not 
only  made  possible,  but 
also  is  sustained.  What 
the  conditions  would  be 
were  these  invisible  agents 
to  cease  their  beneficent 
work  of  scavenging  can  be 
scarcely  imagined.  Life 
as  we  know  it  on  this-  earth 
could  not  exist  were  these 
dust-plants  not  present. 

All  animal  life  is  de- 
pendent directly  or  indirectly  upon  the  vegetable 
kingdom  for  sustenance.  Man  takes  both  animal  and 
vegetable  food,  but  he  is  not  able  to  manufacture  this 
food  out  of  the  inorganic  elements.  X 

Plants  use  for  their  food  gases,  water,  and  various 
salts  usually  dissolved  in  the  water.     In  sunlight  the 


FIG.  30.  A  VARIETY  OF  PEA. 

(a)  Grown  in  soil  with  the 
proper  nitrifying  bac- 
teria. 


(b) 


Grown  under  the  same 
conditions  without  the 
bacteria. 


50  HOUSEHOLD   BACTERIOLOGY 

green  leaves  through  their  chlorophyl  cells  are  able 
to  take  most  of  their  carbon  from  the  carbon  dioxide 
of  the  air.  Some  oxygen  is  also  taken  from  the  air, 
but  most  of  it  is  absorbed  by  the  rootlets  from  the 
ground  air,  the  water  in  the  soil,  or  from  organic  com- 
pounds in  solution  in  the  water.  Hydrogen  is  ob- 
tained from  water  and  other  compounds  containing 
hydrogen  and  is  taken  in  through  the  rootlets. 
Nitrogen  No  plants  can  take  their  nitrogen  directly  from  the 
Direct  air.  Although  this  gas  with  oxygen  comprises  the 
major  part  of  the  atmosphere  in  which  all  vegetation 
is  bathed,  it  is  not  taken  in  through  the  leaves  as  the 
carbon  dioxide  is. 

A  government  bulletin  says :  "Ever  since  anything 
has  been  known  in  regard  to  plant  nutrition  and  the 
necessary  part  that  various  gases  and  minerals  play 
in  the  successful  growing  of  crops,  scientific  men  have 
realized  the  great  importance  of  conserving  the  world's 
store  of  nitrogen  and  have  made  every  effort  either  to 
husband  or  to  increase  all  available  sources  of  supply. 
In  the  early  days,  when  it  was  first  realized  that 
nitrogen  was  so  essential  to  plant  life — in  fact,  was  at 
the  very  foundation  of  agriculture — no  particular 
alarm  was  felt.  Botanists  had  demonstrated  that  plants 
obtained  their  carbon  from  the  carbon  dioxide  of  the 
air,  and  since  this  gas  is  present  in  so  much  less  quan- 
tity than  nitrogen  it  was  believed  that  by  no  possible 
means  could  the  most  essential  of  plant  foods  be  ex- 
hausted. However,  when  it  was  shown  that  plants 


WORK  OF  BACTERIA  51 

were  unable  to  use  free  atmospheric  nitrogen  and 
must  obtain  it  directly  from  the  soil  in  a  highly  or- 
ganized form,  the  importance  of  the  problem  increased 
greatly,  and  the  gravest  consequences  were  predicted 
by  those  familiar  with  the  rapidity  with  which  this 
valuable  element  was  being  wasted." — Farmers'  Bulle- 
tin No.  214,  Beneficial  Bacteria  for  Leguminous 
Crops. 

Nitrogen  in  combination  available  for  plant  food  is     waste  of 
wasted  in  many  ways.    Food  and  other  organic  wastes, 
as  sewage,  are  burned  or  run  into  the  sea  instead  of 
being  returned  to  the  earth,  which  is  the  natural  place 
of  disposal. 

There   are   natural   sources   of   stored   nitrogen   in 
saltpeter  beds  and  guano  deposits,  but  these  are  rapidly 
disappearing.    Even  if  they  were  sufficient  in  quantity  • 
they  are  not  everywhere  present  and  therefore  must 
be  expensive.    Their  aid  would  not  be  available  for  all. 

The  bacteria  are  more  generally  present  and  ready     Nitrifying 
to  work.     Although  unknown  and  therefore  uncred-     Bacteria 
ited,  they  have  been  working  during  all  the  ages  since 
vegetation  appeared,  not  only  by  their  general  agency 
in  producing  fertility  of  the  soil  through  the  products 
of  decomposition,  but  also  in  certain  plants  through 
their  ability  to  take  from  the  air  its  free  nitrogen. 

From  the  earliest  days  of  agriculture  it  has  been 
recognized  that  all  plants  belonging  to  the  leguminosae 
have  a  decidedly  beneficial  effect  upon  the  soil.  Plin> 
wrote:  'The" bean  ranks  first  among  the  legumes. 


HOUSEHOLD  BACTERIOLOGY 


Nitrogen 
Traps 


Enrich 
the  Soil 


Inoculating 
the  Soil 


It  fertilizes  the  ground  in  which  it  has  been  sown  as 
well  as  any  manure."  The  lupine  and  vetch  are  also 
mentioned  in  ancient  writings  as  enriching  the  soil  and 
supplying  the  place  of  fertilizers. 

On  the  roots  of  these  leguminous  plants,  clovers, 
alfalfas,  peas,  beans,  etc.,  are  seen  little  nodules  which 
have  been  found  to  be  filled  with  bacteria.  Fig.  29. 
If  these  "nitrogen  traps"  are  absent  or  are  removed 
the  plants  are  less  vigorous.  Fig.  30  shows  the  com- 
parative size  of  two  plants  of  a  variety  of  pea;  (a) 
grown  on  soil  containing  the  proper  kind  of  bacteria; 
(b)  grown  in  the  same  conditions  and  soil,  but  with- 
out the  bacteria.  The  nitrogen  is  stored  up  in  the 
knots,  swellings,  or  nodules  on  the  roots. 

Not  only  do  these  nitrifying  bacteria  thus  feed  the 
plants  which  carry  them,  but  also  when  the  plants  de- 
cay they  enrich  the  soil  in  which  the  plants  grow.  Soils 
"run  out,"  as  the  farmers  say,  that  is,  there  is  not  plant 
food  enough  to  sustain  luxuriant  vegetable  life.  Here 
is  a  place  for  the  legumes  to  supply  with  their  tiny 
balls  of  bacteria  the  nitrogen  which  has  been  with- 
drawn. In  some  way,  not  understood,  the  clover  or 
similar  plant  in  company  with  the  bacteria  stores  up 
nitrogen  from  the  air,  which  is  finally  returned  to  the 
soil  when  the  decomposition  bacteria  have  accom- 
plished their  work,  thus  making  the  soil  richer  in 
nitrogen. 

When  the  proper  kind  of  nitrifying  bacteria  are  not 
present,  the  scientist  comes  to  the  aid  of  the  farmer 


WORK  OF  BACTERIA 


53 


and  supplies  him  with  artificially  grown  bacteria  with 
which  he  may  inoculate  the  soil  or  seed.  If  the  soil 
is  favorable  otherwise,  the  crop  is  greatly  increased 
and  in  time  the  soil  made  more  profitable  for  other 
crops. 

The  wise  farmer  does  not  plant  potatoes  or  corn 
in  the  same  piece  of  ground  two  years  in  succession, 
unless  he  adds  large  quantities  of  fertilizer  or  plant 
food.  He  rotates  his  crops  because  different  species 
of  plants  take  from  the  soil  different  kinds  or  amounts 
of  food. 

Even  if  these  two  fields  of  work — scavenging  and 
aid  in  agriculture — were  all  in  which  we  make  use  of 
bacteria,  their  claim  of  helpfulness  would  be  over- 
whelmingly proved ;  but  other  results  of  decomposition 
processes  are  valuable  in  the  arts  and  in  the  commerce 
of  the  world. 

By  the  action  of  bacteria  upon  the  whitish  juice  of 
certain  plants  fermentation  processes  are  set  up  which 
result  in  the  blue  indigo  so  important  in  dyeing  indus- 
tries. Our  grandmothers  would  have  been  surprised 
indeed  had  they  understood  that  their  solid  bluing  was 
once  a  white  liquid. 

Bacteria,  too,  make  possible  the  retting  of  the  flax, 
whereby  the  fibres  are  separated  from  the  stalk  to  be 
finally  woven  into  the  beautiful  "pictures  in  white" 
we  call  table  damask. 

They  bear  their  part  in  the  preparation  of  sponges 
and  in  many  processes  of  tanning  and  tobacco  curing. 


Rotation 
of  Crops 


Fermentation 
Processes 


54 


HOUSEHOLD  BACTERIOLOGY 


Flavor 
Production 


In  these  "maceration  industries"  advantage  is  taken 
of  Nature's  methods  of  decomposition  and  what  she 
did  for  countless  ages  before  man  studied  her  "ways 
and  means"  he  still  lets  her  do  for  his  own  and  the 
world's  commercial  benefit.  Her  bacterial  agents  are 
as  ready  to  work  on  the  large 
scale  of  his  planning  as  on 
the  small  scale  of  the  stems 
of  mignonette  left  too  long 
without  fresh  water  in  a  vase 
on  our  tables. 

Yet  these  are  not  all.     Not 
only  do  they  act  directly  and 
indirectly   in   furnishing   food 
to    plants,    which    afterward 
become   food  or  fuel  to  ani- 
mals and  man,  and  prove  a  source  of  wealth  to  man 
in  his  industries,  but  they  also  greatly  increase  the 
variety  and  the  palatability  of  his  food. 

Milk  as  we  know  it  always  contains  bacteria  and 
is  an  excellent  culture  material  for  their  growth.  Such 
a  universal  condition  suggests  some  important  results 
to  be  attained. 

Most  housewives  know  that  while  cream  may  be 
sour  it  is  not  so  sharply  acid  as  the  milk  from  which  it 
was  taken.  The  addition  of  a  little  salt  or  sugar  and 
spices  may  counteract  this  acidity  and  the  result  be 
a  most  delicious  sauce.  The  large  amount  of  fat  in 


Fig.  31.     A  Bacterium  Which 
Makes  Milk  Sour. 


BUTTER  MAKING  . 


55 


the  cream  is  not  a  favorable  food  for  the  lactic  acid 
bacteria.     Fig.  31. 

BUTTER  MAKING 

Butter  is  usually  made  from  sour  or  "ripened" 
cream  and  this  ripening  is  the  work  of  bacteria.  The 
bacteria  which  cause  the  ripening  are  of  different 
species,  which  grow  best  at  different  times  and  under 
different  conditions.  As  the  re- 
sult of  their  growth  are  pro- 
duced many  different  odors  or 
flavors  in  the  cream  and  the 
butter.  Those  that  make  the 
most  desirable  flavor,  aroma  or 
taste  flourish  best  in  May  or 
June  in  this  part  of  our  country. 
Therefore,  butter  made  from 
cream  ripened  by  these  bacteria  has  the  qualities  which 
have  made  "June  butter"  a  synonym  for  the  best. 
Figs.  32  and  33. 

Conditions  over  which  the  housewife  has  little  con- 
trol may  interfere  with  the  products.  If  the  weather 
be  warm  and  moist,  the  cream  and  butter  need  dif- 
ferent care  than  when  the  temperature  is  low,  the  air 
dry  or  the  climate  equable.  She  therefore  tries  to 
produce  an  artificial  climate  by  putting  her  cream  and 
churn  in  a  cold  room  and  the  butter  in  the  refrig- 
erator. 


Fig.      32.      A      Bacterlui 
Which  Gives  a   Pleas- 
ant Odor  to  But- 
ter.    (After 
Conn.) 


Butter 
Bacteria 


56  HOUSEHOLD  BACTERIOLOGY 

This  flavor  production  is  a  true  process  of  fermen- 
tation or  decomposition  and  like  any  other  must  be 
stopped  at  just  the  right  time  or  results  most  undesir- 
able will  be  obtained. 

The  skilled  butter  maker  knows  how  careful  she 
must  be  with  dairy  floor  and  shelves,  milk  pans,  skim- 
mer and  churn  as  well  as  with  the  milk,  the  time  of 

skimming,  the  temperature 
and  age  of  the  cream,  etc. 
From  milk  kept  in  some 
dairies  it  is  impossible  to 
make  good  butter  —  the 
wrong  kind  of  bacteria  are 
there.  This  is  usually  the 
result  of  uncleanness 
somewhere,  it  may  be  out- 
Fig.  33.  A  Bacterium  which  side  the  dairy  or  it  may  be 

Makes  Good   Tasting  But-  .,,. 

ter.  Within. 

This   natural   process   of 

cream  ripening  may  do  for  the  small  home  dairy  where 
all  milk  and  its  care  can  be  under  constant  supervision ; 
but  in  the  public  creamery,  which  receives  milk  from 
many  breeds  of  cows  under  varying  conditions,  such 
chance  ripening  would  lead  to  failures  and  much 
financial  loss. 

June  Flavor          When  a  pink  or  a  rose  is  found  to  have  a  peculiar 

Bacterium      fragrancej   color,  or   shape,   or   to   keep   longer   than 

others,  and  this  is  perpetuated  by  cultivation,  why  not 

a  certain  "June  flavor"  bacterium?    This  is  just  what 

is  done.    Fig.  34. 


BUTTER  MAKING 


57 


The  first  experiment  in  the  culture  of  "butter 
bacilli"  was  made  from  a  specimen  of  milk  which  came 
from  South  Africa  and  was  exhibited  at  the  World's 
Fair  in  Chicago  in  1893. 

This  was  named  from  the  scientist  who  introduced 
the  culture,  "Conn's  Bacillus  No.  41." 

Now  there  are  other  varie- 
ties which  are  cultivated  for 
the  purpose. 

The  butter  of  different 
countries  varies  much  like 
that  of  different  dairies'  in  the 
same  country.  Now,  any  de- 
sired flavor  may  be  obtained 
if  a  pure  culture  of  the  proper 
bacterium  is  used  and  the 
conditions  of  manufacture  are 
understood  and  carried  out. 

The  culture  introduced  into 
the   cream    is    known    in 
United  States  as  a  "starter." 

There  are  different  meth- 
ods of  using  the  starter,  but  one  in  common  use  may 
be  outlined  thus :  "The  pure  culture  is  added  to  a 
small  portion  of  Pasteurized  milk  and  allowed  to 
grow.  At  the  right  time  and  temperature  a  certain 
amount  of  this  'starter'  is  added  to  the  Pasteurized 
cream."  All  the  factors  of  success  are  kept  under 
control ;  nothing  is  left  to  chance.  The  extreme  meas- 


the    Fi&-   34-     A   Bacterium   Which 
Is   Cultivated  and   Sold 
to     Butter     Makers. 
(After   Conn.) 


'Starters" 


HOUSEHOLD  BACTERIOLOGY 


Bad 

Flavor 


Ripening 
Cheese 


ures  taken  to  insure  cleanliness  are  a  revelation  even 
to  the  neatest  housewife. 

Not  all  bad  flavors  in  butter  are  due  to  the  wrong 
bacteria  or  to  molds.  The  food  and  physical  condition 
of  the  cow  may  affect  the  flavor  of  the  milk  and  there- 
fore of  the  butter,  but  certain  distinctive  tastes  or 
appearances,  as  an  oily  or  soapy  taste,  bitter  or  ropy 
milk,  red,  blue  and  other  colors  in  milk,  which  were 
formerly  attributed  to  diet  or 
disease  in  the  cow  are  now  be- 
lieved to  be  the  work  of  various 
micro-organisms.  Fig.  35. 

These  are  diseases  in  the  milk 
as  much  as  the  fermentations  in 
our  bodies  brought  about  by 
germs  of  consumption  or  diph- 
theria are  diseases.  Both  are 
the  work  of  germs  which  have  gained  access  through, 
or  are  working  under  wrong  conditions. 

Health  in  the  human  body  as  well  as  health  in  food 
supplies  means  conditions  unfavorable  for  the  growth 
of  any  germs  or  those  conditions  favorable  only  for 
the  growth  of  helpful  forms.  For  this  end  the  bac- 
teriologist is  always  working. 

CHEESE 

Cheese  is  made  from  the  casein  of  the  milk  and  is 
a  most  valuable  proteid  food.  However,  it  is  seldom 


Fig.      35.      A      Bacterium 

Which   Makes  Milk 

Bed. 


CHEESE 


59 


used  as  food  until  a  ripening  process  has  been  carried 
on  which  gives  it  the  most  desired  flavor  and  increases 
the  digestibility  of  the  albuninous  matter  by  making 
it  easier  of  solution.  The  change  of  the  liquid  milk 
into  the  solid  curd  is  a  chemical  change,  but  to  nu- 
merous species  of  bacteria  and  molds  we  are  indebted 
for  the  many  varied  flavors  which  tickle  the  nerves  of 
taste. 

Certain  species  grow  best 
in  damp,  dark  caves,  and 
some  of  the  foreign,  strong, 
highly-flavored  cheeses  are 
ripened  in  these  caves. 

Some  species  produce 
large  quantities  of  gas' which 
puffs  up  the  cheese  or  leaves 
holes,  large  or  small,  few  or 
many,  according  to  the  num- 
ber of  bacteria 

Fig.  36. 

In  some  kinds  of  cheese,  large  holes  are  made  in 
the  finished  product  and  mold  spores  inserted.  These 
grow  and  give  the  characteristic  flavor  to  the  food. 
This  is  seen  in  the  "Roquefort"  which  was  first  made 
in  a  French  village  of  that  name  from  sheep's  milk. 
Brie,  Stilton,  and  Gorgonzola  are  also  allowed  to  gain 
flavor  from  molds,  while  the  Edam  is  inoculated  with 
a  bacterium.  Sometimes  the  fermentations  develop 
poisonous  products  of  putrefaction  which  may  result 


present.  Fig.     36.       A     Bacterium     Which 
Makes  "Swelled"  Cheese. 


Molds  in 

Ripening 
Cheese 


60  HOUSEHOLD  BACTERIOLOGY 

in  ptomaine  poisoning.     This  would  be  putrid  cheese. 

As  with  cream,  so  the  cheese  curd  may  be  inoculated 
with  the  particular  germ  which,  by  its  growth  and  life 
processes,  is  known  to  give  the  desired  flavor,  just  as 
a  person  may  be  inoculated  with  a  certain  disease  germ. 
In  both  the  processes  are  similar,  although  the  results 
are  different. 

Bacteria         If  cheese  be  made  from  boiled  or  Pasteurized  milk 

forCFiav«     or  from  that  to  which  a  germicide  has  been  added,  the 

ripening  process   does  not  go  on,   showing  that  the 

living  micro-organism  is  necessary  to  the  production 

of  the  desired  flavors. 

Pure  cultures  are  now  used  for  cheese  ripening  and 
therefore  cheeses  that  have  heretofore  been  imported, 
because  the  species  of  bacterium  necessary  was  not 
native  to  this  country,  may  now  be  made  here  when  the 
conditions  of  growth  are  understood. 

Butter  and  cheese  are  possibly  the  most  common 
foods  whose  desirable  and  varied  flavors  are  due  to 
bacteria  and  molds,  but  there  are  others  where  their 
work  is  often  productive  of  a  pleasant  taste. 

VINEGAR 

Anyone  who  has  seen  a  cider  mill  in  operation  in 
the  country  or  has  seen  the  cider  made  "while  you 
wait"  at  a  city  fair  knows  the  process  by  which  the 
whole  apple  is  crushed  and  the  Juice  extracted.  Such 
juice  must,  of  course,  be  seeded  with  wild  yeasts  i 
with  bacteria  which  were  on  the  skin  of  the  fruit 
in  the  air.  When  it  runs  directly  from  the  press 


VINEGAR 


61 


is  only  very  slightly  acid,  but  if  allowed  to  stand  for 
a  while  it  becomes  sharply  acid.  This  acetic  acid 
is  the  result  of  bacterial  growth  and  finally  turns  the 
sweet,  pleasant  drink  into  hard  cider  or  cider  vinegar. 

Fig.  37- 

The  process  of  change  is  a  complex  one,  due  to 
both  chemical  and  bacteriological  agencies.    When  the 


FIG.    37.     BACTERIA    WHICH    MAKE    ACETIC    ACID    AND    VINEGAR. 
(After  Conn.) 

wild  yeasts  have  brought  about  the  alcoholic  fermenta- 
tion of  the  sweet  apple  juice  certain  bacteria  take  up 
the  work  and  produce  acetic  acid  in  a  weak  solution 
which  we  know  as  vinegar.  There  are  different  spe- 
cies capable  of  producing  acetic  acid  of  different 
strengths  and  under  different  conditions.  What  is 
known  as  the  mother-of-vinegar  is  a  dense  mass  of 
bacteria — a  true  zooglcea  form.  Fig.  38. 


Sugar  to 
Acetic  Acid 


62 


HOUSEHOLD  BACTERIOLOGY 


Butyric 
Acid 


These  are  the  agents  which  make  the  vinegar. 
Not  all  vinegar  used  in  the  household  is  made  from 
cider.      The  large  manufactories  usually  use  alcohol 
or  wine  as  the  base  of  the  process.    Alcojiol  and  acetic 
acid  contain  the  same  elements  in  different  porportions, 
the    former    having    less    oxygen.      The    bacteria    of 
mother-of -vinegar  are  able  to  take  oxygen  from  the 
air,  cause  it  to  unite  with  the  alcohol,  and  thus  make 
acetic  acid.     In  actual  practice  a  weak  alcoholic  solu- 
tion    is     allowed     to    trickle 
slowly  over  beechwood  shav- 
ings.   In  this  way  a  large  sur- 
face is  exposed  to  the  air.    It 
is  found  that  if  the  shavings 
are   sterilized,   that   is,   if   all 
micro-organisms  are  removed, 
no  acetic  acid  is  formed,  thus 
proving   that   here   again   we 
ln     are  indebted  to  our  dust-plant 

friends. 

Lactic  acid,  the  acid  of  sour  milk,  and  acetic  acid, 
the  acid  of  vinegar,  are  two  desirable  acids  due  to 
bacterial  growth,  while  a  third,  butyric  acid,  not  desir- 
able to  the  housewife,  results  when  such  growth  takes 
place  in  fats.  This  is  the  chief  cause  of  rancidity  in 
butter  and  other  oily  substances  and  the  similar  taste 
or  smell  in  old  milk.  To  the  housewife  this  means 
loss  of  food  supplies  and  therefore  comes  under  the 
unfriendly  work  of  dust-plants. 


FIG.     38.         Bacteria 
"Mother-of -Vinegar. 


HARMFUL  DUST-PLANTS 

The  harmful  work  of  bacteria  and  molds  so  far  is 
seen  to  consist  of  two  kinds,  the  production  of  unfavor- 
able conditions  in  food  supplies,  and  in  or  on  other 
property,  as  mildew  on  clothes,  books  or  furnishings; 
in  short,  diseased  conditions  of  our  possessions.  These 
diseases,  if  not  cured,  may  be  serious  enough  to  destroy 
the  property,  while  they  may  also  cause  similar  diseased 
conditions  in  our  own  bodies,  more  or  less  severe, 
which  may  result  in  death. 

Bacteria  sour  our  milk,  our  sauces,  our  fruit  juices;     LifeWork 
they   not   only    "ret"    the   flax    when   we   wish    them     Jj^g1 
to,  but  they  rot  wood  when  we  do  not  want  them  to ; 
they    make    meat    putrid    and    butter    rancid ;    molds 
spoil  our  bread  and  jellies  and  clothes.  All  these  things 
the  dust-plants  will  do  unless  we  prevent  them,  be- 
cause they  are  in  the  world  to  soften,  to  decompose, 
and  thus  to  "get  rid  of  what  has  ceased  to  live."    All 
such  substances  are  food  for  them  and  feeding  is  their 
way  of  working. 

We  must  know  how  to  prevent  their  work  when  it 
interferes  with  our  interests.  We  must  prevent  their 
growth  by  removing  conditions  which  are  favorable  or 
we  must  kill  them. 

An  experiment  which  anyone  can  try  will  suggest 
what  favorable  or  unfavorable  conditions  are  and  in 
what  way  science  seeks  to.  help  the  housewife  to  pre- 
serve both  her  property  and  her  health. 


64  HOUSEHOLD  BACTERIOLOGY 

Experiment  III.  Take  seven  clear  glass  bottles, 
Experiments  number  or  mark  each  in  some  way.  (Small  laboratory 
Bacteria  flasks  with  flat  bottoms  are  convenient  for  this  pur- 
pose.) Put  into  each  one-half  cup  or  less  of  milk  or 
grape  juice. 

Leave  No.  I  open  in  a  warm  room,  not  in  direct 
sunshine. 

Fit  No.  2  with  a  full  plug  of  cotton  wool  about  one 
inch  long.  Put  with  No.  i. 

Have  No.  3  like  No.  i,  but  place  immediately  in  an 
ice  box. 

Drop  into  No.  4  one  tablet  or  "saloid"  of  corrosive 
sublimate.  This  can  be  bought  of  a  druggist.  Mark 
it  "Poison."  Plug  like  No.  2  and  place  it  with  No.  I. 

Plug  No.  5  with  cotton  wool  like  No.  2.  Put  it  into 
a  steamer  and  steam  for  thirty  minutes  three  days  in 
succession.  Place  it  with  No.  i. 

Fit  No.  6  with  a  tight  cork.  Remove  the  cork,  but 
place  it  with  the  bottle  in  the  steamer  and  steam  as 
you  did  No.  5.  Cork  each  bottle  while  the  steam  is 
coming  out.  As  the  cork  cools  and  shrinks,  tighten  it. 

Put  a  cotton  wool  plug  into  No.  7  and  heat  for  half 
an  hour  from  155°  F  to  165°  F. 

After  completed  preparation,  keep  all  but  No.  3 
under  the  same  conditions  and  note  any  changes  that 
occur.  Test  the  open  bottles  with  strips  of  blue  litmus 
paper  from  the  druggist's.  See  if  the  contents  change 
the  paper  any  more  rapidly  or  completely  after  two  or 
three  days  than  at  first.  Test  by  smell  and  taste  all 


HARMFUL  BACTERIA  65 

but  No.  4,  the  one  in  which  was  put  the  corrosive 
sublimate.  This  is  a  poison  to  human  beings  when 
taken  internally. 

No.  I  is  open  to  air  and  dust  and  in  time  will  be- 
come sour  or  undergo  fermentation.  If  left  long 
enough  the  milk  may  putrify. 

No  2  is  closed  to  dust  but  not  to  air.  However, 
no  pains  was  taken  to  free  the  bottle  or  plug  from  the 
dust  which  was  on  them  or  in  the  contents,  so  in  time 
this  will  become  sour. 

No.  3  has  all  the  conditions  of  No.  I  except  warmth, 
which  is  favorable,  .and  light,  which  to  some  dust 
plants  is  unfavorable.  It  should  not  spoil  or  sour  as 
quickly  as  No.  I. 

No.  4  has  been  treated  by  a  chemical  which  is  poi- 
sonous and  should  kill  the  dust-plants  present.  This, 
if  strong  enough  to  kill,  is  a  disinfectant.  If  only 
strong  enough  to  prevent  or  retard  growth  for  a  while 
it  would  be  an  antiseptic.  There  should  be  no  change 
in  No.  4. 

No.  5  will  have  been  sterilized,  that  is,  all  life  within     intermittent 
liquid,    or    bottle,    killed    by    the    steaming    process.     sterilization 
The  first  steaming  is  expected  to  kill  all  the  growing 
or  vegetative  forms  then  present.  It  may  not  be  enough 
to  kill  any  spores  that  are  there.     These  will  be  en- 
couraged to  grow  by  the  greater  heat,  but  on  the  sec- 
ond day  they  will  have  developed  into  the  ordinary 
growing    form   and   the    steaming   should    kill    them. 
That  sterilization  may  be  assured  and  any  possibly 


66  HOUSEHOLD  BACTERIOLOGY 

resisting  microbe  destroyed,  a  third  steaming  is  given. 
This  is  called  intermittent  sterilization.  No.  5  should 
keep  indefinitely.  It  will,  of  course,  dry  away  slowly 
through  evaporation. 

No.  6  is  like  No.  5,  only  closed  from  the  air  which 
passes  through  the  cotton  wool,  an^fjae  cork  was 
sterilized  it  is  impervious  to  dust.  Sfl  Berks  are  not 
solid  enough  to  keep  the  bacter  Hi  growing 

HK 


through  the  cavities.  Such  corks  be  dipped 

in  melted  paraffin.  They  are  theji  as  tight  as  a  glass 
stopper.  No.  6  should  keeg,  as!  Hi  No.  5. 

The  woman  who  put  up  her  ]  ^^juice  in  corked 
bottles,  to  find  some  years  after  that  she  had  gp^pe 
wine,  either  did  not  thoroughly  sterilize  the  juice,  the 
bottles  and  the  corks,  or  the  latter  allowed  dust  to  pass 
or  mold  to  grow  through.  She  should  have  covered 
the  corks  with  melted  paraffin  to  prevent  such  a  pos- 
sibility. 

NO.  7  varies  from  No.  5  only  in  the  time  and  the 
degree  of  heat  to  which  it  was  subjected.  In  the  case 
of  milk  —  where  the  process  is  most  commonly  used  — 
this  is  called  Pasteurization.  It  is  sufficient  to  kill 
most  if  not  all  the  souring  bacteria  and  all  the  disease- 
producing  or  pathogenic  germs.  It  does  not  affect  as 
unfavorably  the  digestibility  of  the  milk  as  steriliza- 
tion, 212°  F,  or  higher  is  found  to  do. 

Pasteurized  milk  will  spoil  eventually  because  not 
all  the  germs  are  killed.  Pasteurization  is  valuable  for 
protection  -from  disease  germs  and  to  improve  the  keep- 


PRESERVING  FOOD  67 

ing  qualities  of  milk  or  cream.  As  it  is  not  a  process 
of  sterilisation,  such  milk  sometimes  grows  putrid  or 
bitter  without  souring. 


FIU.   39.     Diagram   Showing   Effect  of  Pasteurization  Upon  Milk. 

Fig.  39  represents  the  change  which  takes  place  in 
the  germ  content  of  milk  during  this  process.  If  we 
represent  the  germ  content  of  a  sample  of  raw  milk 
by  the  size  of  the  white  square,  then  the  black  square 
will  show  the  same  after  Pasteurization. 

All  additions  of  bacterial  poisons  are  liable  to  injure 


68  HOUSEHOLD  BACTERIOLOGY 

the  persons  using  the  milk;  therefore,  in  most  cases, 
such  additions  are  contrary  to  law. 

PRESERVING  FOOD 

The  following  from  the  U.  S.  government  bulletin 
on  "The  Use  and  Abuse  of  Food  Preservatives,"  will 
show  us  that  man  has  always  sought  to  prevent  the 
use  of  his  food  by  these  micro-organisms : 

"In  hot,  arid  regions  the  question  of  the  preservation 
of  food  is  of  little  interest.  An  animal  may  be  slain 
and  its  carcass  hung  in  the  air  to  dry.  Other  foods 
keep  correspondingly  well.  Putrefaction  and  decay 
are  almost  unknown.  On  the  other  hand,  wherever 
climatic  conditions  favor  decay  this  question  becomes 
important,  especially  for  those  who  live  at  a  distance 
from  markets  and  who  kill  and  preserve  their  own 
meat,  and  for  those  who,  either  on  land  or  sea,  are 
for  a  number  of  days  remote  from  a  source  of  supply. 

"The  methods  most  commonly  employed  for  pre- 
serving  food,  by  drying  and  smoking  and  with  salt, 
vinegar,  alcohol,  and  sugar,  have  long  been  known. 
Some  of  them  are  probably  as  old  as  civilization  itself, 
and  indeed  are  not  unknown  to  many  tribes  of  savages. 
We  are  told  by  Herodotus  that  the  ancient  Egyptians 
were  conversant  with  the  art  of  preserving  meat  with 
salt,  and  six  centuries  before  the  Christian  era  Cyrus 
sustained  his  troops  on  long  expeditions  with  salted 
meat.  The  aborigines  of  North  and  South  America 
were  accustomed  to  cure  their  meat  by  smoking  or 
"jerking"  (tearing  from  the  bone  in  long  strips  and 


PRESERVING  FOOD  69 

drying  in  the  sun)t  according  to  the  requirements  of 
the  climate.  The  preservation  of  meat  by  salting,  dry- 
ing, and  smoking  is  practiced  in  Oriental  countries  by 
a  number  of  the  Mongolian  tribes,  including  the  Tar- 
tars and  the  Chinese. 

"It  is  a  matter  of  common  information  that  these 
methods  are  still  employed  largely  in  civilized  coun- 
tries and  not  alone  by  those  in  rural  districts  who 
preserve  their  own  meat.  Our  large  packing  houses 
smoke  immense  quantities  of  meat  with  hickory  wood. 
One  establishment  in  Chicago  has  43  smokehouses, 
each  of  which  holds  60,000  pounds  of  ham  or  shoulder 
or  120,000  pounds  of  side  meat,  besides  n  houses  of 
half  that  capacity.  Meat  so  preserved  is  recognized 
as  wholesome.  It  is  not  always  suitable  for  the  sick 
room,  but  its  taste  is  a  sure  indication  of  its  character 
and  the  method  of  its  preparation.  This  makes  it  im- 
possible to  mistake  these  products  for  fresh  meat,  and 
thus  removes  the  great  temptation  to  fraudulent  prac- 
tice that  attends  the  use  of  tasteless  preservatives.  The 
preservation  of  meat  by  freezing  has  always  been 
practiced,  and  in  localities  where  the  temperature  fa- 
vors this  method  nothing  else  is  to  be  desired.  Until 
recently,  however,  this  method  has  necessarily  been  of 
limited  application.  *  *  * 

"No  tasteless  food  preservative  has  been  suggested 
which  is  entirely  nontoxic,  and  which  does  not  have  a 
marked  influence  on  digestion,  even  when  taken  in 
relatively  small  doses.  Some  there  may  be  whose  anti- 


70  HOUSEHOLD  BACTERIOLOGY 

septic  action  is  so  slight  that  food  treated  with  the 
minimum  amount  necessary  for  its  preservation  is  not 
unwholesome  for  adults  in  normal  health.  But  in  any 
case  food  so  treated  should  be  plainly  labeled  with  the 
name  and  amount  of  the  added  preservative." 

sugar  Condensed  milk  keeps  because  most  of  the  water 
has  been  taken  out  and  a  large  percentage  of  sugar 
added.  This  results  in  a  thick,  pasty  mass,  enclosing 
very  little  air,  in  which  the  few  germs  which  survive 
the  heating  that  the  milk  undergoes  cannot  grow  and 
work.  Decomposition  is  thus  retarded  or  prevented  so 
long  as  the  milk  is  not  exposed  to  any  fresh  deposit  of 
dust.  The  contents  of  an  open  can  will  soon  show 
mold  or  give  other  evidence  of  spoiling  and  when  di- 
luted to  the  consistency  of  ordinary  milk  will  sour  like 
fresh  milk. 

Drying  Fifty  years  ago  the  country  housewives  dried  their 
own  apples,  plums,  raspberries  and  blueberries  for 
winter  use.  This  drying  of  uncooked  fruits  is  simply 
an  antiseptic  measure  and  they  must  be  kept  dry  or 
they  will  spoil.  They  must  also  be  carefully  cleaned 
before  use.  Some  of  the  germs  are  killed  by  the  dry- 
ing process,  but  others  enter  the  spore  stage  and  are 
ready  for  work  when  moisture  is  furnished. 

canned         The  present-day  housekeeper  owes  much  of  the  vari- 

Goods     etv  jn  ker  f00(}  SUppiy  to  the  possible  preservation  of 

fruits  and  vegetables  through  sterilization.     "Canned 

goods"  are  sterilized  by  means  of  steam  or  boiling. 

The  same  process,  of  course,  cooks  the  food,  thereby 


PRESERVING  FOOD  71 

killing  any  bacteria  or  other  germs  which  might  be 
in  the  vegetable  or  animal  tissues.  The  cans  are  sealed 
while  hot. 

In  the  household  similar  processes  are  carried  on. 
To  insure  success,  everything  which  touches  the  food 
should  be  sterilized — the  jar  and  its  cover,  spoons, 
ladles  or  funnel.  Hands  and  towels  should  not  touch 
the  edges  of  the  mouth  of  the  jar  nor  the  inside  of  the 
cover,  for  they  may  carry  dust  enough  to  reinfect  the 
fruit. 

When  the  canned  food  ferments  or  spoils  it  means  .<Sp0iling» 
that  in  some  way  it  was  not  thoroughly  sterilized  or 
that  dust-plants  gained  access  to  it  afterward.  Where, 
sugar  is  used  it  should,  of  course,  be  put  in  before  the 
sterilization,  not  afterward,  unless  it  is  made  into  a 
syrup  and  sterilized  by  boiling.  If  the  housewife  re- 
members that  everything  is  dusty;  that  dust  means 
dust-plants ;  that  dust-plants  mean  the  germs  of  fer- 
mentation and  putrefaction,  or  "spoiling;"  that  noth- 
ing short  of  sterilization  will  insure  indefinite  "keep- 
ing," she  will  know  with  what  she  is  dealing  and  may 
act  intelligently. 

If  all  dust  could  be  removed  from  the  air,  the  latter 
might  have  free  access  to  her  cans  and  no  souring 
would  follow.  They  might  dry  up,  but  they  would  not 
"spoil."  If  the  jar  of  food  be  completely  sterilized, 
it  can  be  stored  anywhere  in  light  or  dark,  warm  or 
cold  places ;  no  fermentation  occurs.  But  the  chances 
of  partial  sterilization — a  misnomer,  of  course,  for  such 


HOUSEHOLD  BACTERIOLOGY 


Acids  as 
Preservatives 


Essential 
Oils 


Salt 


a  condition  is  not  one  of  sterility — are  so  many  that 
the  cold  place  adds  the  antiseptic  "ounce  of  preven- 
tion." So  far  as  the  bacteria  are  concerned,  in  the 
sunshine  would  be  the  best  place  to  keep  such  stores. 
This,  however,  would  in  time  fade  the  food  and  under 
some  conditions  would  help  to  dry  it,  or  crystallize  the 
sugar.  Here,  as  elsewhere,  there  must  often  be  a 
choice  among  unfavorable  conditions. 

Some  food  supplies,  like  rhubarb,  are  so  strongly 
acid  that  bacteria  will  not  grow  in  them.  This  is  some- 
times canned  in  cold  water  with  no  cooking.  Toma- 
toes and  cranberries  are  sometimes  canned  in  this  way. 

Bacteria  do  not  like  strong  acids,  so  the  housewife 
saves  her  cucumbers,  tomatoes,  etc.,  by  making  them 
into  pickles.  These,  however,  will  mold. 

The  essential  oils,  as  clove,  cinnamon,  mustard,  etc., 
are  antiseptic  in  their  effects.  They  possibly  lend  their 
aid  in  the  preservation  of  the  fruit  as  well  as  in  adding 
flavor.  Mustard,  especially,  has  strong  disinfecting 
properties.  Perhaps  this  is  its  greatest  value  as  a  con- 
diment, for  it  may  act  upon  the  bacteria  liable  to  cause 
fermentation  in  the  digestive  tract. 

Strong  solutions  of  salt  prevent  the  growth  of  bac- 
teria. Common  salt,  both  in  brine  and  as  powder, 
is  perhaps  the  oldest  preservative,  and  although  it 
makes  most  food  stuffs  less  digestible  it  is  probably 
the  least  harmful  of  any  antiseptic  substances.  This 
cannot  be  said  of  borax,  boracic  acid,  salicylic  acid, 
the  sulphites  and  formaldehyde  (formalin)  ;  all  of 


PRESERVING  FOOD  73 

which  when  strong  enough  to  hinder  the  growth  of 
bacteria  are  thought  to  interfere  more 'or  less  with  the. 
digestive  processes  of  man.    The  use  of  any  such  sub- 
stance is  prohibited  by  the  U.  S.  pure  food  law. 

It  would  seem  that  eggs  at  least  should  be  free  from     Clean 
bacteria  because  of  their  enclosing  shells.    But  experi-     Eggs 
ments  have  shown  that  the  newly-laid  egg  is  sometimes 
infested   with   bacteria  and  their  growth   may   bring 
about  the  decomposition  of  the  egg. 

The  more  common  danger,  however,  is  that  of  un- 
clean conditions  of  nest  or  storage.  The  shell  is  porous 
to  air  and  also,  it  has  been  found,  to  certain  bacteria. 
The  shells,  then,  should  be  clean.  Eggs  are  often  pre- 
served by  a  coating  of  shellac  or  in  lime  water.  These 
methods  exclude  air,  without  which  any  germ  inside 
cannot  grow,  and  they  prevent  any  germ  on  the  out- 
side from  passing  through  the  shell. 

We  see,  then,  why  eggs  should  be  kept  in  a  clean, 
cool  place,  and  if  packed,  the  packing  boxes  or  material 
should  be  clean.  Eggs  are  often  tainted  by  moldy 
packing  boxes,  sour  hay,  or  dirty  straw. 

Some  of  the  less  common  acts  of  bacteria  are  inter- 
esting even  if  we  suffer  by  them. 

Fig.  49  shows  a  plate  which  was  placed  on  the  out-     Dust  Garden 
side  sill  of  a  second-story  window  on  the  back  of  a  city     oiTof  Doors 
house.    This  window  overlooked  an  open  field  border- 
ing on  a  large  body  of  water.     It  was  not,  therefore, 
an  especially  dusty  position  and  the  day  was  quiet,  with 
little  wind,     The  fact  that  so  many  dust-plants  were 


74  HOUSEHOLD  BACTERIOLOGY 

caught  in  the  twenty  minutes'  exposure  shows  the  con- 
dition in  which  uncovered  jellies,  puddings,  sauces, 
etc.,  are  likely  to  be  when  placed  in  such  places  to  cool ; 
therefore,  it  is  not  rsurprising  that  lemon  jelly,  jellied 
meat,  etc.,  are  sometimes  found  in  a  liquid  condition  in 
such  a  place. 

As  we  have  said,  some  of  the  bacteria  are  capable 
of  liquefying  gelatine.  If  the  right  species  of  bacteria 
had  happened  to  be  present  in  the  dust  which  settled 
in  this  place,  nothing  could  have  prevented  the  gelatine 
being  liquefied,  because  the  presence  of  the  liquefying 
bacterium  would  have  been  unknown  until  its  work 
had  been  done.  A  slight  liquefaction  is  shown  at  the 
largest  spot  in  Fig.  46. 

The  teacher  who  followed  a  lesson  on  the  dangers 
of  dust  by  one  on  lemon  jelly  which  she  placed  uncov- 
ered in  the  open  window  to  cool,  did  not  apply  the 
scientific  knowledge  which  she  had.  If  she  had  done 
as  well  as  she  knew,  the  contents  of  her  mold  would 
have  remained  jelly  and  not  become  lemonade. 


DISEASE  GERMS 

We  have  seen  that  these  dust-plants  may  spoil  our 
property  and  thereby  cause  us  much  expense.  Did 
they  do  nothing  else,,  we  might  not  spend  so  much  time 
or  labor  in  studying  them  and  their  work. 

Just  as  among  the  hundreds  of  beautiful  flowers  in 
the  woods  and  fields  there  is  a  "poison  dogwood ;"  or 


FIG.  40.     THE  BACILLUS  OF  TUBERCULOSIS, 
(a)     Taken  from  lung  tissue,     (b)     As  sometimes  found  in  the  sputum. 

among  the  luscious  mushrooms  a  deadly  "Amanita;" 
or  as  in  a  great  city  among  the  thousands  of  honest, 
harmless,  law-abiding  citizens  there  is  an  occasional 
thief  or  murderer;  so  among  the  millions  of  helpful 
bacteria  there  are  a  few  which  in  man  and  animals 
cause  disease  of  greater  or  less  virulence. 

These  are  called  infectious  or  contagious  diseases. 
They  are  carried  either  by  actual  contact  with  dis- 

75 


Communicable 

Diseases 


HOUSEHOLD  BACTERIOLOGY 


No  Germs 
No  Disease 


Favorable 
Conditions 


eased  tissues ;  by  inhaled  dust,  as  most  often  in  tuber- 
culosis or  consumption ;  or  by  food  or  drink  in  which 
was  the  germ  which  is  capable  of  causing  a  specific 
disease — as  typhoid  fever,  diphtheria,  etc,  or  through 
some  wound  in  the  skin.  Figs.  40,  41,  42. 

If  the  specific  germ  of  typhoid  fever,  tuberculosis 
or  pneumonia,  etc.,  is  not  pres- 
ent the  disease  will  not  appear, 
no  matter  how  "run  down"  or 
"below  par"  the  person  may  be. 
But  any  condition  short  of  nor- 
mal health — any  weakening  of 
the  body  by  cold,  indigestion, 
fatigue,  overheating,  lack  of 
nourishment,  etc.,  tends  to  lessen 
the  resistance  in  some  part  or 
the  whole  of  the  body  and  makes 
the  attack  of  any  germ  which 
comes  along  more  surely  suc- 
cessful. 

Any  inherited  weakness,  as 
weak  lungs,  sluggish  circulation, 
imperfect  digestive  powers,  in- 
creases the  danger  or  liability  to 
attacks  of  germ  diseases.  Given  the  germ  under  fa- 
vorable conditions  for  its  growth,  it  is  then  a  question 
of  the  resistant  power  of  the  individual,  aided,  per- 
haps, by  medical  science,  whether  the  body  or  the  dis- 
ease will  gain  the  victory. 


FIG.       41.         Bacillus     of 

Diphtheria. 
(After    Conn.) 


DISEASE  GERMS 


77 


It  is  believed  by  some  scientists  that  the  commonly 
prevalent  species  of  bacteria,  harmless  under  ordinary 
conditions,  may  change  their  character  when  settled 
in  thickly  crowded  centers  of  population  where  dark- 
ness, dampness,  bad  air,  insufficient  or  poor  food  make 
filthy  habits  of  life.  If  these  then  gain  access  to  human 
tissues  they  may  develop  disease-producing  power  and 
be  carried  far  and  wide.  In  this  way  cholera,  the 
"plague,"  and  similar  diseases,  beginning  in  countries 
or  sections  of  cities  where  human  beings  herd  together 
with  no  pretense  of  cleanliness,  are  carried  across  seas 
and  continents.  This  would  show  how  necessary  to 
the  physical  health  of  the 
world  is  the  purification  of 
"the  slums,"  whether  these 
occur  at  home  or  abroad. 
Other  bacteriologists  deny 
this  hypothesis,  but  how- 
ever the  disease  germs  may 
have  developed  their  evil  ways,  they  never,  so  far  as 
we  know,  reform  of  their  own  accord  and  become 
harmless,  although  unfavorable  conditions  may 
weaken  their  power  or  virulence. 

The  bacteria  which  are  the  cause  of  typhoid,  diph- 
theria, or  tuberculosis  make  a  specialty  of  this  work. 
The  true  parasitic  disease  germs  affecting  man  must 
have  human  beings  in  which  to  propagate  with  any 
degree  of  success ;  so  the  human  body  is  the  chief 
natural  breeding  ground  of  contagious  disease  germs. 


Origin 
of  Disease 
Germs 


FIG.   42.    Typhoid  Bacillus   Show- 
ing  the   Many   Cilia. 
(After   Sedgwick    and    Wilson.) 


Breeding 
Ground 
for  Germs 


HOUSEHOLD  BACTERIOLOGY 


Point  of 
Attack 


Method  of 
Infection 


Precautions 


Outside  of  the  body  disease  producing  bacteria  may 
remain  alive  under  very  varying  circumstances,  but  as 
a  rule  they  do  not  multiply  as  most  of  them  require  a 
temperature  equal  to  that  of  the  body.  There  are  ex- 
ceptions, as,  for  example,  the  growth  of  the  bacteria 
of  typhoid  fever  in  milk,  and  many  others  which 
reproduce  in  the  laboratory  under  artificial  conditions. 
The  lower  animals  may  serve  as  a  breeding  ground 
for  some  of  the  disease  germs  dangerous  to  man. 

For  most  of  these  germ  diseases  there  is  some  spe- 
cial portion  of  the  body  which  is  more  susceptible  than 
any  other.  We  associate  pneumonia  and  usually  tu- 
berculosis with  the  lungs,  diphtheria  with  the  throat, 
typhoid  fever  with  certain  parts  of  the  intestines.  From 
these  most  usual  points  of  attack  may  be  inferred  the 
most  common  methods  of  infection. 

When  the  seat  of  the  disease  is  some  portion  of  the 
respiratory  system — nostrils,  throat  or  lungs — it  is 
probable  that  dust  entering  with  the  inhaled  air  car- 
ried the  germ,  or  it  came  by  contact  with  the  lips,  as 
in  kissing;  when  it  is  in  the  digestive  tract,  that  food 
or  drink  was  the  vehicle ;  or  when  in  the  skin  or  outer 
tissues,  that  there  was  actual  contact  with  the  germ 
either  as  dust,  dirt,  or  germ  bearing  material  from  a 
previous  case  of  the  disease,  which  gained  entrance 
through  some  puncture  or  a  break  in  the  skin. 

When  we  remember  that  all  such  diseased  condi- 
tions due  to  germs  are  infectious,  we  shall  exercise 
great  care  in  preventing  contact  with  the  diseased 


DISEASE  GERMS  79 

part  or  with  articles  which  have  come  into  contact 
with  it.  It  should  prevent  the  use  of  the  mouth  as  a 
"third  hand"  for  holding  miscellaneous  articles;  the 
moistening  with  saliva  of  envelopes  or  of  fingers  to 
turn  leaves,  etc.,  which  thence  may  carry  infection  to 
the  next  user.  We  should  think  of  the  danger  to 
others  as  well  as  to  ourselves. 

This  is  one  of  the  objections  to  a  common  comb 
and  hairbrush,  towel,  etc.  All  ready-made  gar- 
ments worn  next  the  skin  should  be  washed  before 
wearing.  All  garments  made  under  "sweatshop"  con- 
ditions should  be  avoided,  because  of  the  danger  of 
contagion,  if  for  no  other  reason.  Clothes  subject 
to  any  infectious  discharge,  as  handkerchiefs,  towels, 
etc.,  should  not  be  washed  with  other  clothes.  When 
possible,  all  such  discharges  should  be  received  upon 
paper  or  cloths  that  can  be  burned  immediately.  It 
is  well  to  take  this  much  forethought  for  the  laun 
dress. 

Especially  with  such  diseases  as  tuberculosis,  pneu-  careof 
monia,  and  diphtheria,  absolute  care  should  be  taken 
that  the  sputa  or  discharges  from  the  nostrils  and 
throat  as  in  sneezing  or  coughing,  are  not  thrown  off 
into  the  air  to  become  a  part  of  the  common  dust. 
When  the  person  himself  is  able  to  control  the  dis- 
charge he  should  remember  that  he  may  thus  re-in- 
fect himself  and  also  spread  the  disease.  Infected  or 
soiled  articles  should  be  immediately  disinfected, 
burned,  or  boiled.  If  this  cannot  be  done  at  once, 


8o 


HOUSEHOLD  BACTERIOLOGY 


they  should  be  kept  wet,  then  the  germs  cannot  easily 
be  spread  about  except  by  flies. 

Lockjaw  .An  exception  to  the  usual  characteristics  of  disease 
producing  germs  is  a  bacillus  which  is  common  in  the 
soil  of  certain  localities, — the  germ  of  the  usually 
fatal  disease  known  as  tetanus  or  lockjaw.  Fig.  43. 
The  living  germ  or  its  spore  is  carried  into  the  warm, 
moist  tissues  through  a  wound  in  the  skin.  This  us- 
ually is  made  with  some  sharp  object  which  has  come 
in  contact  with  the  ground,  as  a  nail,  a  rake  tooth, 
a  pitch-fork,  or  a  dirty  knife. 
It  has  been  known  to  follow 
the  bite  of  an  insect.  Unlike 
most  disease  germs,  this  bac- 
terium forms  spores  which 
makes  it  very  tenacious  of  life. 
Its  spores  will  resist  boiling  or 
drying  for  some  time.  It  is 
said  to  have  been  found  in  gun- 
powder which  would  account 
for  many  the  cases  of  lock- 
jaw resulting  from  gunshot 

wounds.  As  a  result  of  celebrating  the  Fourth  of  July 
in  1903,  415  deaths  from  lockjaw  occurred  in  the 
United  States.  This  number  dropped  in  1904  to  105,  in 
1905  to  104,  and  in  1906  to  89.  This  decrease  was 
brought  about  through  the  proper  care  of  wounds  and 
the  use  of  tetanus  antitoxine.  Wounds  should  be 
cleaned  thoroughly  and  not  bound  up  tightly,  as  the 


FIG.    43.      The    Bacillus 
of    Lockjaw; 


DISEASE  GERMS  81 

exclusion  of  air'  favors  the  growth  of  the  tetanus  ba- 
cillus. Its  characteristic  spore  at  one  end  of  the  rod 
has  given  it  the  name  of  the  "drum  stick"  bacillus. 

In  general  it  may  be  concisely  stated  that  infection 
comes  through  inhaled  dust  and  that  "Food  and  fingers 
are  the  carriers  of  contagion,"  as  Dr.  William  T. 
Sedgwick  has  so  often  proved. 

The  disease  bacteria  effect  their  dread  results  in 
various  ways ;  sometimes  the  tissues  are  actually  de- 
stroyed, as  in  tuberculosis,  but  in  most  cases  the  prod- 
ucts of  the  life  growth  of  the  germs  cause  the  disease. 
These  products  are  poisons  which  are  known  under  the 
general  name  of  toxines. 

Whether  in  the  future  the  germ  theory  will  be  found 
to  explain  all  diseases  we  may  not  now  say,  but  indi- 
cations point  that  way.  The  latest  "discovery  of  the 
germ  of  smallpox,"  if  established,  is  a  stimulus  to 
increased  efforts  along  such  lines.  Animal  and  vege- 
table forms,  are  both  proved  guilty  before  the  bar  of 
the  scientific  investigator. 

The  germ  of  typhoid  fever  grows  well  in  milk. 
The  germ  may  enter  the  milk  as  dry  dust  from  any 
one  of  many  contaminated  sources,  or  through  water 
in  which  the  milk-containing  vessels  are  washed.  In 
cases  of  dishonest  milkmen,  from  the  water  used  to 
dilute  the  milk.  Numerous  epidemics  of  typhoid  fever 
have  been  traced  to  milk  as  their  source,  where  only 
those  using  milk  from  one  farm  or  from  a  certain 
milkman  have  been  affected. 


82  HOUSEHOLD  BACTERIOLOGY 

That  the  germ  may  retain  its  vitality  through  all 
the  processes  of  butter-making  is  proved  by  its  pres- 
ence in  samples  of  butter  examined. 

It  is  not  always  easy  nor  possible  to  find  the  source 
of  single  cases  of  this  or  any  disease,  for  the  infectious 
germ,  carried  as  dust,  may  lodge  on  any  article  and 
be  thus  carried  to  the  mouth  by  food  or  by  hands, 
infection         Oysters,   fattened   on  sewage-polluted  water,   have 
by  oysters      carrje(f  the  germ  to  persons  eating  them.     Clams  dug 
out  of  sewage-saturated  flats,  when  eaten  raw,  may 
carry  the  typhoid  germ  in  a  similar  manner, 
sewage         In  country  places  where   wells   are  the  source  of 
drinking  water,  or  anywhere  where  surface  waters  are 
used  directly  for  this  purpose,  there  is  great  danger 
of  contamination  from  drainage,  either  from  the  house, 
its  outbuildings,  the  barn,  or  manured  fields.     Con- 
taminated water  supply  is  the  most  common  source  of 
typhoid  infection. 

As  the  germs  causing  the  disease  are  thrown  out  in 
the  discharges  from  the  intestines  and  the  kidneys, 
these  are  the  sources  of  infection.  If  the  discharges 
from  the  patient  and  any  articles  soiled  by  these  are 
not  destroyed  by  fire  or  thoroughly  disinfected  while 
moist,  there  can  be  no  surety  that  they  may  not,  either 
as  dust  or  through  water,  carry  infection  to  someone 
nearby  or  even  far  removed.  If  such  care  be  taken 
for  every  case  of  the  disease,  it  will  soon  be  no  more 
prevalent  than  smallpox. 

Every  case  of  typhoid  fever  is  due  to  somebody's 


DISEASE  GERMS  83 

criminal  carelessness,  because  in  the  eye  of  the  law      XiTeMne 
ignorance  is  not  accepted  as  an  excuse.     Somewhere 
there  has  been  neglect  of  the  cleanness  or  care  which 
ought  to  have  made  infection  impossible. 

When  rain  starts  from  the  clouds  it  is  pure,  but  in  Pollution 
falling  through  the  air  it  washes  out  from  the  air  large 
quantities  of  dust,  so  that  the  first  fall  of  any  shower 
is  very  dirty.  Where  rain  water  is  collected  for  drink- 
ing or  cooking  purposes  this  first  fall  should  be  allowed 
to  waste  or  the  whole  be  thoroughly  filtered  before 
its  use  in  cooking.  The  cistern  also  must  be  kept  clean 
and  free  from  dust  pollution.  It  should  be  sheltered, 
but  not  air-tight.  Such  a  water  supply  is  seldom  pol- 
luted by  sewage  or  any  human  wastes.  It  is  water 
running  on  the  surface  of  the  ground  or  draining 
through  it  which  may  encounter  sewage  pollution  and 
thus  be  most  liable  to  take  up  disease  germs. 

Snow  filters  the  air  even  more  than  rain,  each  con- 
gealed flake  usually  containing  many  bacteria.  The 
first  snow,  although  white  and  pure  to  look  at,  is  not 
clean  and  should  not  be  used  as  a  source  of  drinking 
water  except  in  emergencies.  However,  after  the  snow 
has  been,  falling  for  some  time  the  water  from  it  is 
practically  clean. 

Light  always  retards  and  in  many  cases  prevents 
the  development  of  harmful  micro-organisms.  But  this     of  Light 
disinfectant  action  does  not  extend  to  all  depths,  prob- 
ably not  much  beyond  nine  feet,  so  that  its  purifying 
agency  in  open  water  supplies  is  only  partial.    A  water 


84 


HOUSEHOLD  BACTERIOLOGY 


Purifying 
Water 
Filters 


Porcelain 
Filters 


supply  which  receives  any  house  drainage  or  that  from 
manured  fields  is  in  danger  of  contamination  at  any 
time. 

Impure  water  may  be  purified  from  all  germs  by 
boiling  for  half  an  hour.  Such  water,  having '  lost 
the  air  which  was  dissolved  in  it,  tastes  insipid.  The 
air  may  be  restored  by  pouring  the  water  a  few  times 
from  one  clean  vessel  into  another,  and  this  should  be 
done  in  a  clean  place,  that  is,  where  there  is  little  fly- 
ing dust. 

Most  filters  simply  strain  out  visible  suspended  mat- 
ter or  invisible  but  comparatively  large  animal  or  veg- 
etable forms.  A  flannel  bag  will  do  this,  and  it  can 
and  should  be  cleaned  daily.  It  clears  currant  jelly, 
why  not  water?  When  charcoal  forms  a  part  or  the 
whole  of  the  straining  medium,  more  organic  matter 
is  removed  and  therefore  more  color  is  taken  out,  but 
the  charcoal  soon  loses  its  purifying  power -and  must 
be  cleaned  or  renewed.  None  of  the  ordinary  faucet 
filters  will  remove  the  minute  disease  germs  and  there- 
by make  a  polluted  water  safe  for  drinking.  Germ 
removal  requires  a  very  fine  medium,  which  means 
slow  straining.  Certain  filters,  made  of  very  fine  un- 
glazed  clay  or  similar  substance,  take  out  the  germs 
themselves,  but  cannot  remove  the  products  of  their 
life  processes,  which  are  soluble.  In  some  cases  these 
are  as  dangerous  as  the  germ  plant  itself.  If  a  filter 
does  strain  out  the  bacteria,  then  it  is  evident  that 
the  straining  medium  will  become  foul  with  them  and 


DISEASE  GERMS  85 

must  be  capable  of  and  receive  complete  sterilization. 
Any  faucet  filter  which  allows  a  generous  stream  of 
water  to  issue  quickly  after  it  is  turned  on  is  practical- 
ly useless  so  far  as  the  removal  of  bacteria  is  con- 
cerned. 

A  suspected  water  or  one  of  unknown  quality  would      niter 

Thou 

better  be  filtered  and  then  boiled  rather  than  boiled  and  BOU 
filtered,  if  it  needs  to  be  filtered  to  remove  suspended 
matter.  Distilled  water  or  water  turned  into  steam 
and  condensed  is  a  pure  water;  but  to  remain  so  it 
must  be  received  into  perfectly  clean  vessels  and  not 
exposed  to  dust. 

Ice  as  ordinarily  delivered  frequently  shows  three  Ice 
layers.  One,  usually  at  the  top,  the  snow  ice,  is  scarce- 
ly transparent  and  when  melted  shows  impurities  not 
visible  in  the  ice.  This  usually  holds  many  bacteria 
and  should  always  be  rejected.  Another  layer,  par- 
tially transparent,  is  more  or  less  bubbly.  These 
bubbles  contain  air  which  allows  any  living  forms 
therein  to  remain  alive  if  not  to  grow.  If  derived 
from  impure  water  the  bubbles  may  contain  some 
of  the  germs  which  will  make  the  ice  undesirable, 
since  many  bacteria  survive  a  lower  temperature  than 
ice  ever  attains.  A  third  portion  is  wholly  trans- 
parent. This  last,  the  crystal  clear  ice,  is  the  only  ice 
which  should  ever  be  used  directly  to  cool  drinking 
water,  for  this  alone  is  purified  by  crystallization  al- 
though not  perfectly. 

Ice  should  always  be  washed  from  surface  dirt  before 


86  HOUSEHOLD  BACTERIOLOGY 

it  is  put  into  a  refrigerator  or  in  any  way  used  for  the 
storage  of  food.  Safety  may  be  assured  if  ice  is  never 
allowed  to  touch  the  food.  Its  effects  can  be  obtained 
without  actual  contact  and  contact  may  mean  con- 
tamination. 

The  tub  of  lemonade  standing  open  on  the  picnic 
ground  or  the  street  corner  has  sufficient  chance  of 
germ  infection  without  a  block  of  doubtful  ice  in  its 
midst. 

THE   RESISTANCE    OF    THE   BODY   TO    DISEASE    GERMS 

sources  of          We  have  seen  that  many  diseases  which  afflict  hu- 

Inlection  T- 

man  beings  have  been  definitely  traced  to  these  or- 
ganic forms ;  to  these  micro-organisms  found  in  in- 
haled dust,  in  polluted  water,  in  food  and  on  articles 
which  may  puncture  the  skin. 

If  the  avenues  of  infection  are  so  common,  the  ques- 
tion naturally  arises,  how  can  any  human  being  escape  ? 
We  know  that  many  do,  that  there  are  hundreds  of 
persons  who  never  have  had  typhoid  fever,  diphtheria, 
or  other  infectious  disease ;  that  two  persons  may,  so 
far  as  we  know,  eat  of  the  same  food,  drink  from  the 
same  water  supply  or  live  under  exactly  similar  con- 
ditions— one  has  some  infectious  disease,  the  other  re- 
mains well. 

It  is  too  a  matter  of  common  knowledge  that  a  de^- 
gree  of  safety  from  a  second  attack  is  often  assured  to 
the  person  after  recovery  from  the  first  illness.  He 
seems  to  have  some  power  of  resistance  which  he  did 
not  have  before  and  which  is  absent  in  his  neighbor. 


RESISTANCE  OF  THE  BODY  87 

Yet  this  safety  is  not  always  complete,  because  some 
persons  have  recurring  attacks  of  infectious  diseases. 
This  is  especially  true  in  diphtheria. 

There  seems  to  be  some  power  in  the  robust,  healthy, 
strong  body  which  is  absent  in  the  weak  and  "ailing" 
or  in  the  body  "below  par,"  as  the  physicians  say. 
Whatever  this  power  is  it  may  well  be  referred  to  as 
"vital  resistance." 

Dr.  William  Sedgwick  says,  "There  is,  however,  no 
quantitative  measure  of  vital  resistance;  but  when  it 
is  regarded  as  small  or  altogether  wanting,  the  term 
is  no  longer  used,  and  the  organism  is  said  to  be  not 
vitally  resistant,  but  "susceptible"  or  "vulnerable"  to 
disease.  *  *  *  When  the  vital  resistance  is  com- 
plete *  *  *  the  organism  is  said  to  be  immune." 

At  present  no  one  perhaps  knows  all  the  factors 
which  go  to  make  up  this  "vital  resistance"  which  pro- 
tects one  person  and  is  absent  in  another,  but  accord- 
ing to  Sedgwick,  "We  may,  it  is  true,  safely  consider 
that  it  is  bound  up  with  chemical  and  physical  pro- 
cesses which  result  in  favorable  chemical  and  physical 
conditions." 

In  this  connection  it  should  be  noted  that  the  hy- 
drochloric acid  in  the  gastric  juices  of  the  adult  is 
fatal  to  nearly  all  of  the  ordinary  bacteria  present 
in  uncooked  food  and  to  many  disease  germs.  The 
secretions  of  the  intestines,  are  alkaline  and  would  prove 
a  favorable  condition  for  many  kinds  did  they  escape 
from  the  stomach.  Water  passes  quickly  through  the 


Vital 
Resistance 


Gastric 
Juices 


f  0'  THE 

I    UNIVERSITY 

V .-^.  OF       J 


HOUSEHOLD  BACTERIOLOGY 


Health 


Theories 

of  Vital 

Resistance 


Leucocyte 


stomach  and  may  not  mix  with  the  acid  juices,  con- 
sequently it  is  an  especially  dangerous  medium  of  in- 
fection. 

Health  means  the  prevention  in  all  possible  ways  of 
any  chance  of  attack  from  the  insidious  disease  germ, 
but  it  means  as  well  the.  observance  of  all  other  laws 
that  tend  toward  the  maximum  efficiency  of  the  body 
and  mind,  so  that  if  the  enemy  gains  admittance  it  may 
be  routed  or  its  attack  made  futile. 

Much  has  been  done  along  the  lines  of  investiga- 
tion, yet  much  of  these  processes  of  resistance  remain 
to  be  proved.  A  few  words  concerning  the  theories 
put  forth  by  investigators  may  show  our  indebtedness 
to  them  and  increase  our  own  sense  of  responsibility 
toward  the  preservation  or  return  of  health. 

Among  the  red  cells  which  give  the  familiar  color 
to  good,  rich  blood  are  other  cells  known  as- the  white 
globules  or  leucocytes.  They  are  very  much  like  the 
amoeba,  the  lowest  animal  known,  in  that  they  have 
the  power  of  independent  motion.  They  are  some- 
times called  "phagocytes,"  or  "wandering  cells,"  be- 
cause they  pass  here  and  there  throughout  the  body, 
wherever  they  will.  Fig.  44.  Their  office  seems  to  be 
a  protective  one,  for  they  act  like  the  police  of  a  city 
in  protecting  the  body  from  bacterial  invaders.  They 
are  also  called  "eating  cells,"  for  when  one  finds  a  bac- 
terium it  proceeds  to  wrap  itself  about  the  little  plant 
cell,  to  poison,  if  not  to  kill  it ;  then,  loaded  with  the 
dead  bodies  of  its  victims,  it  makes  its  way  to  some 
part  of  the  body  where  the  load  may  be  disgorged. 


RESISTANCE  OF   THE  BODY 


89 


FIG.    44.     (a)    and    (b).     PHAGOCYTES. 

(c)  A  phagocyte  with  partially  enclosed  bacterium. 

(d)  A  phagocyte  with  two  bacteria  enclosed. 

(e)  A  phagocyte  with  enclosed  mass  of  bacteria.     (After  Conn.) 


HOUSEHOLD  BACTERIOLOGY 


Effect 
of  Cold 


Formation 
of  Pus 


It  is  fortunate  for  us  that  there  is  such  a  force  that 
is  hungry  and  ever  seeking  what  and  how  many  it 
may  devour,  for  we  can  never  know  just  how  much 
we  owe  to  them  for  our  freedom  from  disease.  As 
long  as  these  white  globules  are  numerous  and  active, 
so  long  man  seems  to  have  one  powerful  guardian 
against  any  invading  germ,  however  poisonous.  Any- 
thing which  affects  these  white  guardians  unfavorably 
lessens  their  power  to  protect  man. 

Cold  paralyzes  them  and  gives  the  bacteria,  if  pres- 
ent, a  better  chance  to  escape  from  being  overcome, 
and  we  are  thus  more  subject  to  their  attacks.  Win- 
ter's cold  increases  the  prevalence  of  many  germ  dis- 
eases, not  usually  by  increasing  the  number  or  virulence 
of  the  germs  themselves,  but  by  decreasing  in  some 
persons  the  power  of  these  leucocytes — the  guardians 
of  our  health. 

Insufficient  clothing,  or  insufficient  food  which  is 
the  body's  fuel,  may  thus  favor  the  attacks  or  the 
spread  of  germ  diseases.  Very  often  these  phagocytes 
lose  their  lives  in  resisting  our  foes.  Then  they,  with 
their  victims  and  the  dead  tissue  cells, '  form  pus  or 
"matter,"  which  children  even  know  should  be  "let 
out"  in  order  that  the  tissues  may  heal. 

The  formation  of  pus  is  well  illustrated  by  the 
action  of  a  sliver.  We  may  or  may  not  know  that  the 
tiny  speck  of  wood  entered  the  flesh.  But  it  is  likely 
to  carry  in  with  it  dirt  and  therefore  bacteria.  The 
phagocytes  rally  to  surround  this  newcomer.  The  flesh 


RESISTANCE  OF   THE  BODY  gi 

becomes  red,  inflamed  and  sore,  then  a  "fester"  ap- 
pears. Open  the  "fester"  and  a  drop  or  more  of  pus 
exudes,  in  the  midst  of  which  will  probably  be  the 
irritating  sliver.  The  bacteria,  the  cause  of  the  inflam- 
mation, having  passed  out,  the  flesh  heals.  If  there 
has  been  much  bacterial  growth  there  may  be  much 
or  longer  continued  inflammation  because  of  the  tox- 
ines  or  poisonous  matters  produced  by  the  germs. 

When  certain  very  virulent  germs  enter  the  tissues, 
are  unconquered  either  by  the  phagocytes  or  the  other 
resisting  powers  of  the  body,  the  products  of  germ 
growth  may  be  rapidly  distributed  by  the  blood 
throughout  the  body,  producing  the  fatal  cases  of  blood 
poisoning.  The  germ  was  especially  virulent,  in  great 
numbers,  or  possibly  neither  of  these,  but  the  body  was 
so  "far  below  par"  that  it  had  no  power  to  resist  the 
growth  and  action  of  the  germs  and  the  toxines  which 
the  germs  manufactured. 

That  bacteria  capable  of  producing  disease  in  human  Germs 
beings  are  far  more  commonly  present  than  the  diseases 
cannot  be  doubted.  Germs  of  pneumonia  are  found 
in  the  mouths  of  healthy  persons.  Some  persons  when 
exposed  to  infection  succumb ;  others  remain  unaf- 
fected. The  old  saying  that  "lightning  never  strikes 
twice  in  the  same  place"  has  often  been  applied  to  the 
expressed  fear  of  a  recurrence  of  an  infectious  dis- 
ease. Although  there  are  many  exceptions  to  the  rule, 
it  is  true,  as  we  have  said,  that  in  a  majority  of  cases 
after  recovery  from  such  a  disease  there  is  less  dan- 


HOUSEHOLD  BACTERIOLOGY 


Effect  of 
Poisoning 


Immunity 


ger  of  a  second  attack.  There  seems  to  be  great  dif- 
ferences also  between  the  susceptibility  of  children  and 
adults  to  certain  diseases. 

The  different  ways  in  which  bacteria  are  known  or 
supposed  to  bring  about  diseased  conditions  more  or 
less  severe  have  been  described.  Whether  these 
causes  are  the  poisonous  excretions  during  the  nor- 
mal life  of  the  bacteria,  or  are  the  resulfc  of  chemical 
change  produced  by  some  ferment  which  they  secrete, 
the  effects  upon  the  blood  and  tissues  are  shown  by 
several  common  symptoms — a  high  temperature  or 
fever;  quickened  circulation  or  rapid  pulse;  perhaps 
difficulty  in  breathing,  and  pain.  There  may  be  local 
redness,  swelling,  and  finally  the  formation  of  pus,  or 
a  "gathering"  of  the  protective  phagocytes  and  the 
broken-down  cells  of  the  diseased  portion.  These  local 
effects  may  be  entirely  within  the  body  or  they  may  be 
show  themselves  on  the  outside  under  or  in  the  skin. 
In  the  latter  case  a  prompt  discharge  of  the  pus  is 
usually  followed  by  relief.  If  there  be  no  discharge 
and  the  dead  and  poisonous  matter  be  reabsorbed  into 
the  tissues,  there  follows  a  general  poisoning  of  the 
whole  system. 

Whenever  partial  or  entire  immunity  seems  to  be 
present,  we  are  interested  to  know  in  what  this  im- 
munity consists.  Great  as  is  the  protective  force  of 
the  "white  guardians"  their  presence  or  numbers  are 
not  the  only  factors  in  immunity. 

Metchnikoff,  the  father  of  the  theory  of  phagocy- 


RESISTANCE  OF  THE  BODY  93 

tosis — as  the  protective  work  of  these  "eating"  and 
"wandering  cells"  is  called — has  said  that  "immunity 
may  be  inborn  or  acquired."  *  *  *  The  former  is 
independent  of  the  direct  intervention  of  human  art; 
the  acquired  immunity  may  come  as  the  result  of  the 
spontaneous  cure  of  an  infectious  disease  or  as  the 
result  of  direct  interference  of  human  art,  as  in  vac- 
cination and  similar  methods  now  employed  by  phys- 
icians to  ward  off  an  expected  disease  or  to  decrease 
the  virulence  of  one  already  contracted." 

This  inborn  immunity  Newman  calls  "natural  im-     Natural 
munity"  and  attributes  it  to  the  presence  in  the  blood      Immunity 
of  soluble  matters  called  alexines.    If  the  alexfnes  are 
present  in  sufficient  quantity,  the  person  is  less  or  not 
at  all  susceptible  to  certain  diseases,  although  they  may 
not  protect  him  from  the  attack  of  all  disease  germs. 
These   alexines   protect   the  body  perfectly   from   all 
but  the  pathogenic  bacteria. 

Phagocytosis  seems  to  be  a  plausible  theory  so  far 
as  the  germs  themselves  are  concerned,  but  does  not 
prove  equally  tenable  in  the  case  of  the  toxines  which 
the  germs  have  produced.  Other  investigators, 
notably  Behring  and  Kitasato,  do  not  believe  that  the 
phagocytes  are  the  prime  protective  agency  in  this 
immunity.  They  discovered  in  their  experiments  upon 
animals  that  the  clear,  yellowish  liquid  part  of  the 
blood,  or  the  bloom  serum,  taken  from  an  animal  that 
had  diphtheria  could  and  did  in  their  test  tubes  destroy 
the  action  of  the  toxines  of  that  disease. 


94 


HOUSEHOLD  BACTERIOLOGY 


Acquired 
Immunity 


vaccination 


It  seems,  then,  probable  that  in  the  blood  serum  of 
immune  persons  there  may  be  another  factor  in  the 
vital  resistance.  That  is,  the  body  cells  in  some  way 
manufacture  substances  that  neutralize  the  poisons  or 
toxines  produced  by  the  germs,  thus  enabling  the  body 
to  expel  the  germs  themselves,  and  recover.  These 
antitoxines  or  the  power  of  producing  them  may  re- 
main and  the  body  becomes  immune  to  the  disease. 
These  antitoxines  are  specific  in  nature,  —  that  is,  are 
capable  of  neutralizing  the  toxine  of  only  one  kind  of 
germ. 

Immunity  may  also  be  "acquired"  by  the  injection 
into  the  blood,  in  some  cases,  of  the  germs  themselves, 
as  in  the  case  of  inoculation  for  small  pox  as  was 
as  was  originally  done  in  the  case  of  inoculation  for 
small  pox.  Formerly  some  "matter,"  that  is,  the  in- 
fectious material,  was  taken  from  a  person  sick  with 
small  pox  and  injected  directly  into  another  person  by 
placing  it  under  the  skin,  where  it  quickly  affected  the 
whole  body. 

Jenner  —  a  celebrated  doctor  in  England  about  1796 
—  first  modified  inoculation  by  introducing  the  "mat- 
ter" into  healthy  calves  or  cows.  These  animals  be- 
ing very  susceptible  to  the  disease,  contracted  it,  and 
then  from  the  pustules  of  their  bodies  the  "matter" 
or  "vaccine"  was  drawn  and  injected  into  human  be- 
ings. This,  in  man,  was  found  to  produce  a  milder 
form  of  the  disease  and  to  leave  in  the  system  upon 
recovery  something  which  gave  immunity  or  protec- 
tion from  small  pox. 


RESISTANCE   OF   THE  BODY 


95 


Vaccination  or  Jenner's  process  is  still  the  recog- 
nized preventive  or  protective  measure,  and  it  has  re- 
duced small  pox  from  a  dread  pestilence  to  a  disease 
producing  fewer  deaths  than  measles. 

The  great  Pasteur  reasoned  that  "if  an  infectious 
disease  be  really  a  struggle  for  supremacy  between 
man  and  microbe,  it  is  probable  that  in  vaccination  for 
small  pox  the  struggle  is  less  severe  for  the  patient, 
because  the  germs  of  small  pox  have  somehow  been 
weakened  or  enfeebled  by  their  residence  in  the  cow." 

The  use  of  antitoxine  for  the  prevention  or  treat- 
ment of  diphtheria  is  perhaps  the  best  example  of  trnt 
method  of  producing  immunity.  In  this  case  the  horse 
is  chosen  as  the  intermediate  host  for  the  production 
of  antitoxine  material.  The  toxines,  or  sometimes 
the  germs  themselves,  are  injected  into  the  body  of 
the  healthy  animal.  The  first  dose  is  usually  a  small 
one.  A  slight  attack  of  true  diphtheria  follows.  The 
doses  are  gradually  increased  until  the  animal  is  found 
to  be  immune.  Blood  is  then  drawn  from  this  immune 
horse  and  "its  serum  is  found  to  contain  the  anti- 
toxine in  abundance." 

Some  of  this  serum  is  then  injected  into  a  per- 
son who  has  been  exposed  to,  is  likely  to  be,  or  is 
ill  with  the  disease.  In  the  last  case,  to  be  effective, 
the  antitoxine  must  be  introduced  at  an  early  stage  of 
the  disease  when  there  is  not  too  much  toxine  to  be 
neutralized. 

By  the  use  of  antitoxine  thus  obtained,  the  mortality 


Making 
Antitoxine 


Diphtheria 

Antitoxine 


HOUSEHOLD  BACTERIOLOGY 


Nature's 
Disinfectants 


Conditions 
in  the  House 


from  diphtheria  has  been  reduced  over  one  half.  Its 
effects  as  a  preventive  measure  and  in  lessening  suffer- 
ing "have  everywhere  been  most  significant  and  en- 
couraging." Antitoxines  for  lockjaw,  for  snake  bites 
and  for  some  forms  of  blood  poisoning  have  been  pro- 
duced and  are  used  with  more  or  less  success. 

Constant  efforts  are  being  made  to  find  an  available 
antitoxine  for  every  infectious  disease.  Many  diffi- 
culties present  themselves,  because  the  same  germs  do 
not  always  cause  the  identical  disease  when  introduced 
into  the  bodies  of  the  lower  animals  that  they  produce 
in  the  body  of  man. 

SANITATION 

As  sunshine  and  pure  air  are  Nature's  free  disin- 
fectants, their  presence  in  the  house  is  the  greatest  pre- 
ventive measure  of  all  sickness  due  to  micro-organ- 
isms. They,  then,  are  the  foundation  requirements 
for  cleanness,  because  this  means  so  largely  the  ab- 
sence of  dust-plants. 

Inside  our  houses  there  can  never  be  the  same 
amount  of  sunshine  and  fresh  air  that  proves  so  ef- 
ficient out-of-doors.  The  house,  too,  must  be  dry,  and 
therefore  dust  cannot  be  held  as  it  often  is  out  of 
doors  on  damp  surfaces.  However,  the  absence  of 
winds  inside  makes  possible,  after  a  little  while,  a  com- 
paratively dust-free  air,  because  the  heavier  particles 
which  carry  the  bacteria  and  molds  will  settle  on  all 
surfaces,  chiefly  on  the  horizontal  ones,  as  floors, 


SANITATION 


97 


chairs,  shelves,  etc.  Figure  45,  redrawn  from  Dust 
and  Its  Dangers,  T.  Mitchell  Prudden,  shows  how  the 
living  plants  attach  themselves  to  the  other  particles 
of  dust ;  a  is  a  small  bit  of  wood  carrying  four  different 


J.   45.     COLONIES  OP  BACTERIA  GROWING  ON  DUST  PARTICLES. 

(After   Prudden.) 

colonies ;  b  is  a  grain  of  sand  surrounded  by  one  col- 
ony ;  c  a  splinter  of  wood,  is  loaded  with  five  different 
species.  Each  of  these  colonies  is  the  growth  of  five 
days  from  a  single  germ  which  fell  on  the  surface  of 
the  gelatine.  At  the  end  of  five  days  the  largest  was 
only  just  visible  to  the  naked  eye. 

If    a    dust-garden    be    planted    immediately    after 


Sweeping 


HOUSEHOLD  BACTERIOLOGY 


Dust  Gardens 


Settling 

of  Bacteria 

and  Molds 


sweeping  a  carpeted  room  and  another  when  the  same 
room,  with  closed  windows,  has  been  left  undisturbed 
for  two  or  three  hours,  there  is  a  marked  difference 
in  the. number  and  kind  of  colonies  which  will  grow. 

Figures  46  to  49  inclusive  are  photographs  of  "dust- 
gardens"  planted  in  various  places  by  different  persons 
under  varying  conditions.  The  plate  shown  in  Fig. 
46  was  planted  after  a  carpet  had  been  swept  with  a 
dampened  broom.  The  plate  was  left  open  ten 
minutes. 

The  damp  broom  caught  and  held  much  of  the  dust 
which  would  have  been  thrown  into  the  air  if  a  dry 
broom  had  been  used.  If  the  sweeping  had  been  done 
carelessly  without  thought  of  the  dust,  many  more 
plants  would  have  found  their  way  to  the  garden  plot. 
As  it  was,  the  number  of  spots  shows  how  carefully 
sweeping  ought  to  be  done  in  order  that  the  air  may 
not  be  charged  with  dust  which  is  thereby  simply 
changed  in  place,  not  removed  from  the  room.  It 
soon  returns  to  the  floor  or  carpet. 

Plate  Fig.  47  was  exposed  for  ten  minutes  in  the 
same  place  after  the  room  had  been  quiet  for  three 
hours  and  the  dust  had  therefore  settled  considerably. 
The  fewer  spots  show  that  the  air  had  become  much 
freer  from  dust  than  when  Fig.  46  was  planted. 

The  greater  number  of  molds  present  in  this  plate 
shows  that  the  bacteria,  being  heavier,  settle  first.  The 
presence  of  so  many  molds  shows  that  even  after 
three  hours'  quiet,  the  air  may  still  be  sufficiently 


SANITATION 


99 


FIG.  46.  A  PETRI  PLATE  PLANTED  IMMEDIATELY  AFTER  THE 
SWEEPING  OF  A  CARPET. 


ioo  HOUSEHOLD  BACTERIOLOGY 

charged   with   dust  to  cause  trouble   if  food  is  un- 
covered. 

Many  interesting  experiments  have  been  carried  on 
in  hospitals  to  find  how  long  it  takes  for  the  bacteria 
to  settle  out  of  the  air  of  the  wards  after  the  daily 
routine  of  cleaning  and  care  is  over,  or  at  night. 

In  the  Boston  City  Hospital*  it  was  found  that  about 
midnight  after  the  wards  had  been  quiet  for  some 
hours  the  bacteria  had  nearly  all  of  them  settled  upon 
the  floors,  beds,  or  other  articles  of  furniture.  As  soon 
as  the  work  of  the  day  begun  many  of  these,  of  course, 
were  again  thrown  into  the  air.  Dr.  Tucker  found 
that  sweeping  nearly  doubled  the  number  of  germs 
found  in  the  air. 

In  some  experiments  reported  by  Dr.  T.  M.  Prud- 
den  f  it  was  found  that  in  a  carpeted  living  room 
75  bacteria  and  I  mold  settled  on  the  surface  of  the 
exposed  plate  in  five  minutes  before  sweeping,  when 
the  room  was  still.  Immediately  after  sweeping,  a 
similar  experiment  showed  over  2,700  bacteria  and 
6  molds. 

Other  experiments  have  compared  the  numbers 
found  in  a  certain  quantity  of  air  taken  from  houses 
considered  clean  and  those  called  dirty.  The  latter 
showed  about  six  times  as  many  bacteria  as  the 
former. 
Time  for  Compare  Fig.  46  with  Fig.  47  and  decide  the  ques- 

Dusting        

*Report  of  State  Board  of  Health  of  Mass.,  1888. 

|Dust  and  Its  Dangers,  T.  Mitchell  Pruden. 


SANITATION 


101 


I.   47.     THE  SAME  AS   FIG.   46,    AFTER  THE   DUST   HAD  SETTLED 
THREE  HOURS. 


102  HOUSEHOLD  BACTERIOLOGY 

tion  when  dusting  should  be  done,  if  the  aim  of  dust- 
ing be  to  remove  dust  from  the  house.  If,  then,  these 
and  other  experiments  have  shown  that  at  least  two 
hours  are  required  to  free  the  air  of  a  still  room  from 
the  bacteria  present  in  its  dust,  it  is  of  little  use  to 
dust  immediately  after  sweeping.  When  this  is  done, 
no  wonder  the  housewife  exclaims  in  despair,  "Why, 
this  room  was  dusted  this  morning,  but  you  never 
would  have  known  it!" 

While  we  cannot  always  let  two  hours  elapse  be- 
tween some  dust-spreading  process  of  housework,  like 
sweeping  or  bedmaking,  we  can  remember  that  the 
raised  dust  must  settle  before  we  can  remove  it.  Wait 
as  long  as  possible! 

When  Fig.  46  is  compared  with  Fig.  47,  the  reason 
is  plainly  seen  why  rugs  mean  less  dust  than  carpets 
and  therefore  a  cleaner,  healthier  house,  because  these 
can  be  carefully  rolled,  cleaned  out  of  doors,  and  the 
floor  wiped  with  a  damp  cloth. 

Bed-making          Next  to  sweeping  as  a  dust-raising  and  dust-spread- 
ing process  comes  bed-making. 

Fig.  48  shows  a  phte  planted  just  after  a  bed  had 
been  made.  The  colonies  of  bacteria  and  molds  in  this 
plate  had  been  growing  for  a  longer  time  when  the 
photograph  was  taken  than  in  plates  Fig.  46  and  Fig. 
47.  Two  of  the  molds  on  this  plate  are  very  mature, 
being  black  with  spores. 

As  health  requires  that  the  air  of  the  sleeping  room 
be  as  free  from  dust  as  possible,  considerable  time 


SANITATION 


103 


FIG.     48.     DUST    GARDEN     PLANTED     IMMEDIATELY     AFTER     BED- 
MAKING. 


104 


HOUSEHOLD  BACTERIOLOGY 


Removing 
Dust 


Burn 

Sweepinrs 

Wash 

Dusters 


Covet 
Food 


should  elapse  after  bed-making  before  the  dusting  is 
done. 

To  have  a  clean  house,  great  attention  must  be  paid 
to  the  removal  of  dust,  or  dusting.  In  houses  where  this 
is  done  with  a  feather  duster,  bed-making  gives  up 
its  second  place  to  this  dust-spreading,  never  a  com- 
plete dust-removing  process.  Dusting  should  always 
be  done  by  wiping  up  the  dust  into  a  cloth.  When- 
ever possible  to  do  so  without  harm,  the  cloth  should 
be  slightly  dampened  or  oiled.  Dust-plants  are  held  by 
damp  or  oiled  surfaces. 

If,  then,  the  bacteria  do  settle  from  the  air  on  floor 
and  furniture,  and  in  still  places  about  two  hours  is 
necessary  to  effect  this  comparative  clearing  of  the 
air,  these  facts  are  surely  indicated : 

FIRST.  Sweeping  should  be  done  in  such  a  way  as 
to  raise  as  little  dust  as  possible  into  the  air. 

SECOND.  Dusting  should  never  follow  immediately 
after  sweeping. 

THIRD.  Dusting  should  be  a  process  whereby  dust 
is  taken  out  of  the  room,  not  stirred  up  and  thrown 
again  into  the  air.  Cleanness  does  not  result  unless 
the  dust  is  removed  from  the  house. 

All  collections  of  dirt  from  sweeping  should  be 
burned,  and  all  dusters  should  be  washed.  "Burn  the 
sweepings"  and  "wash  the  dusters"  are  two  orders 
which  the  intelligent  housewife  will  obey. 

Dust  in  the  air  settles  on  food  and  thus  produces 
decomposition.  Food  then  should  be  kept  covered  as 


SANITATION 


105 


FIG.   49.     DUST   GARDEN   PLANTED  OUT  OF   DOORS. 


io6 


HOUSEHOLD  BACTERIOLOGY 


Brush 
Clothing 


Deadly 
Dish-Cloths 


Care  of 

Plumbing 


much  as  possible,  cold  and  dry  as  feasible,  to  retard 
the  growth  of  the  micro-organisms  present.  All  foods 
eaten  raw  should  be  thoroughly  cleaned,  especially 
those  that  have  been  exposed  to  dust,  those  grown  in 
or  near  the  earth  or  those  watered  by  house  slops. 

Clothes  should  be  well  brushed,  out  of  doors  if  pos- 
sible ;  those  which  can  be  should  be  washed  frequently, 
boiled  and  sunned.  All  should  be  kept  dry  to  prevent 
mildew,  which  we  know  is  mold. 

That  dish  cloths  and  dish  towels  be  kept  clean  is  as 
necessary  for  health  as  for  clean,  bright  tableware. 
The  greasy  dish  cloth  furnishes  a  most  favorable  field 
for  the  growth  of  germs.  It  must  be  washed  with 
soap  and  hot  water  and  dried  thoroughly  each  time. 
All  such  cloths  should  also  form  a  part  of  the  weekly 
wash. and  be  subjected  to  all  the  disinfection  possible 
with  soap,  r.ot  water,  and  long  drying  in  sunshine 
and  the  open  air.  Beware  of  the  disease-breeding, 
greasy,  and  damp  dish  cloth  hung  in  a  warm,  dark 
place !  Indeed,  no  damp  article  should  ever  be  stored 
in  the  dark.  The  ordinary  sink  cupboard  is  a  warm, 
dark  and  usually  a  damp  place,  which  even  the  plumber 
denounces  as  an  unclean  spot. 

All  waste  and  overflow  pipes,  from  that  of  the 
kitchen  sink  to  that  of  the  refrigerator,  become  foul 
with  grease,  lint,  dust,  and  many  organic  compounds 
that  are  the  result  of  bacterial  action.  They  are 
sources  of  contamination  to  the  air  of  the  entire  house 
and  to  the  food  supply,  thereby  endangering  health. 


SANITATION  107 

The  germs  of  putrefaction  abound  in  dark  places 
and  the  air  becomes  stagnant  and  impure. 

As  the  schoolroom  bears  very  close  relations  to  the 
home,  the  conditions  there  should  be  thought  about  by 
the  housewife.  Either  from  lack  of  time  or  money, 
wrong  methods,  or  too  few  employees,  the  so-called 
cleaning  of  many  schoolrooms  consists  in  a  vigorous 
sweeping  with  dry  broom  or  floor  brush  after  school 
at  night.  The  dust  settles  during  the  night,  but  in 
the  morning,  instead  of  being  taken  away  on  damp  or 
oiled  cloths,  it  is  stirred  into  the  air  again  by  the 
whisking  feather  dusters. 

At  nine  o'clock,  in  troop  the  children,  with  warm, 
moist  throats,  eyelids,  and  nostrils  all  ready  to  catch 
the  floating  germs  which  should  have  been  removed. 

The  housekeeping  of  schoolhouses  needs  intelligent 
supervision  as  well  as  the  mental  and  moral  equip- 
ment of  their  inmates.  Where  so  many  persons  are 
gathered  from  many  kinds  of  homes  the  danger  from 
the  presence  of  disease  germs  must  be  greatly  in- 
creased over  that  of  the  private  house. 

In  dirty  schoolrooms,  poorly  ventilated  by  windows 
and  doors,  compared  with  well  ventilated  rooms,  the 
proportion  of  bacteria  in  the  same  volume  of  air  has 
been  found  to  be  sometimes  as  great  as  six  to  one 
hundred. 

The  cleaning  and  cleanness  of  schoolrooms  should 
certainly  interest  mothers,  next  to  that  of  their  own 
homes.  This  may  be  their  first  civic  duty. 


108  HOUSEHOLD  BACTERIOLOGY 

sanitary  Sanitary  cleanness  requires  the  cleanness  of  the  in- 
dividual,  of  his  possessions,  and  of  his  environment. 
Each  individual  is  directly  responsible  for  his  per- 
sonal cleanness  and  that  of  his  possessions ;  but  over  a 
large  part  of  his  environment  he  has  only  indirect 
control.  Not  until  this  personal  responsibility  is  felt 
in  its  fullest  sense,  and  exercised  in  all  directions  to- 
ward the  formation  and  carrying  out  of  sufficient  and 
efficient  public  laws,  will  sanitary  cleanness  supplant 
the  cure  of  a  large  number  of  diseases  by  their  pre- 
vention. 

When  the  right  of  cleanness  is  added  to  the  right  to 
be  well  fed,  and  both  are  assured  to  each  individual 
by  the  knowledge  and  consent  of  the  whole  people, 
then  the  great  gospel  of  prevention  may  make  good 
its  claim.  Towards  this  ideal  tend  all  the  problems 
which  the  science  of  bacteriology  is  endeavoring  to 
solve.  These  problems  cannot  be  solved  in  the  labora- 
tory alone.  Each  house  in  the  land,  presided  over  by 
an  active,  intelligent  supervisor,  should  become  an  ex- 
periment station  for  the  individual  application  of 
scientific  laws. 


Curd  from  a  good  milk.    Large,  irregular  mechanical  holes. 


Curd  from  a  tainted  milk.    Large,  irregular  mechanical  holes; 
small  pinho'.es  due  to  gas. 


Curd  from  foul  milk. 
THE  WISCONSIN  CURD  TEST 


(Over) 


DIRECTIONS  FOR  MAKING  THE   WISCONSIN  CURD 
TEST 

J.  Q.  EMERY,  Dairy  and  Food  Commissioner,  Madison,  Wis. 

1.  Sterilize  milk  containers  so  as  to  destroy  all  bacteria  in 
vessels.    This  step  is  very  important  and  can  be  done  by  heating 
cans  in  boiling  water  or  steam  for  not  less  than  one-half  hour. 

2.  Place  about  one  pint  of  milk  in  covered  jar  and  heat  to 
about  98  degrees  F. 

3.  Add  ten  drops  of  standard  rennet   extract  and  mix 
thoroughly  with  the  milk  to  quickly  coagulate. 

4.  After  coagulation,  cut  curd  fine  with  case-knife  to  facili- 
tate separation  of  whey;  leave  curd  in  whey  one-half  hour  to 
an  hour;  then  drain  off  whey  at  frequent  intervals  until  curd 
is  well  matted. 

5.  Incubate  curd  mass  at  98  to  102  degrees  F.  by  immers- 
ing jar  in  warm  water.     Keep  jars  covered  to  retain  odors. 

6.  After  6  to  9  hours  incubation,  open  jar  and  observe 
odor;  examine  curds  by  cutting  the  same  with  sharp  knife 
and  observe  texture  as  to  presence  of  pinholes  or  gas  holes. 
Observe  odor 

7.  Very  bad  milks  will  betray  presence  of  gas-producing 
bacteria  by  the  spongy  texture  of  the  curd  and  of  flavor. 

8.  If  more  than  one  sample  is  tested  at  the  same  time,  dip 
knife  and  thermometer  in  hot  water  before  each  time  used. 

"Normal  milk  contains  practically  no  organisms  but  the 
straight  lactic  acid  bacteria.  These  germs  produce  no  gas  and 
no  bad  odors,  but  purely  lactic  acid,  and  the  curd  formed 
therefrom  is  such  as  is  represented  in  Figure  i. 

"Milk  contaminated  by  the  introduction  o/  dust,  dirt,  fecal 
matter,  or  kept  in  imperfectly  cleaned  cans',  becomes  fouled 
with  gas-producing  bacteria  that  break  down  the  milk  sugar 
and  so  produce  gases  and  usually  undesirable  odors ....  There- 
fore milks  showing  the  presence  of  gas  or  bad  odors  in  any 
considerable  degree  are  milks  that  have  been  more  or  less  pol- 
luted with  extraneous  organisms  or  carelessly  handled,  and  as 
a  consequence  such  milks  show  a  type  of  curd  revealed  in 
Figures  2  and  3." — Dr.  H.  L.  Russell.  (For  further 
directions,  see  Farmers'  Bulletin,  No.  84.) 


HISTORY  OF  BACTERIOLOGY 

The  science  of  Bacteriology  is  still  young,  and  like 
normal  youth  is  marked  by  constant,  vigorous  growth, 
yet  the  micro-organisms  with  which  it  deals  are  veri- 
tably antique,  for  the  following  quaint  observation  is 
said  to  have  been  made  two  thousand  years  ago :  "It 
is  to  be  noticed  that  if  there  be  any  marshy  places, 
certain  animals  breed  there,  which  are  invisible  to  the 
eye  and  yet,  getting  into  the  system  through  the  mouth 
and  nostrils,  cause  serious  disorders." 

Later  on  when  the  early  scientists  were  looking 
through  their  very  imperfect  lenses  at  certain  liquids, 
they  saw  many  hardly  visible  moving  bodies.  They 
said,  "Surely  these  moving  things  must  be  alive,"  and 
as  they  had  not  put  anything  into  the  liquids,  it  was 
natural  to  conclude  that  the  little  forms  must  have 
been  spontaneously  generated.  So  great  a  thinker  as 
Aristotle  had  previously  made  a  similar  statement,  for 
when  he  saw  birds  one  morning  flying  about  over  the 
valley  of  the  Nile,  where  the  day  before  not  a  bird 
was  present,  he  devoutly  concluded  that  they  must 
have  been  generated  from  the  mud  of  the  Nile,  that 
great  Father  of  Plenty.  It  is  within  the  memory  of 
some  living  today  that  this  theory  of  spontaneous 
generation  was  still  believed.  .  x* 

About  1675  Leuwenhock,  the  son  of  a  Dutch  lens 
grinder,  saw  through  one  of  his  lenses  in  a  drop  of 
stagnant  water  minute  moving  forms.  Soon  some  of 
the  scientists  became  interested  and  studied  these  "ani- 
malcules" or  little  animals,  as  they  were  called.  They 

109 


Spontaneous 
Generation 
of  Life 


Animalcules 


no 


HOUSEHOLD  BACTERIOLOGY 


Early 

Theory  of 

Fermentation 


Meadow 
Tea 


made  drawings  of  what  they  saw,  which  show  very 
much  the  same  forms  that  would  be  .seen  today  under 
similar  conditions.  Many  scoffed  at  these  reports,  in- 
timating that  such  observers  were  not  wholly  sane. 

The  processes  of  fermentation  and  putrefaction  very 
early  excited  investigation.  Great  efforts  were  made 
to  find  out  their  cause.  For  years  the  oxygen  of  the 
air  was  thought  to  be  the  agent,  and  even  today  many 
a  housewife  will  tell  you  the  jar  of  fruit  spoiled  be- 
cause "the  air  got  into  it."  The  dust-plants  which  are 
in  the  air,  the  real  cause  of  these  changes,  could  not 
be  discovered  until  the  compound  microscope  brought 
to  view  the  hitherto  invisible  life  which  swarms  in  all 
fermenting  and  putrefying  matter. 

The  compound  microscope  was  invented  in  the  early 
part  of  the  seventeenth  century,  by  whom  is  not 
known.  It  was  not  brought  to  its  present  simple  but 
effective  form  until  about  sixty  years  ago. 

One  of  the  first  sources  of  bacteria  for  these  early 
investigations  is  still  a  common  and  sure  source. 

Take  a  wisp  of  hay  and  soak  it  in  lukewarm  water 
for  a  day  or  so.  The  result  is  a  brownish  liquid  look- 
ing much  like  tea,  which  it  is,  being  an  infusion  of 
hay.  Thoreau  called  this  "meadow  tea."  A  drop  of 
this  under  the  microscope  furnishes  a  lively  menagerie, 
as  well  as  numerous  bacilli.  The  hay  is  dusty;  in  the 
dry  dust  are  spores  of  bacteria  which  under  the  influ- 
ence of  the  warmth  and  moisture  become  once  again 
active  forms  and  can  be  seen  to  go  through  all  their 
life  processes. 


HISTORY   OF   BACTERIOLOGY 


in 


A  drop  of  water  from  the  neglected  vase  of  flowers 
will  often  give  similar  interesting  phenomena. 

The  modern  work  upon  bacteria  was  begun  and  the 
foundations  of  the  science  of  Bacteriology  were  laid 
when  Louis  Pasteur  in  France,  less  than  sixty  years 
ago,  began  to  grow  and  cultivate  these  dust-plants. 
Since  then  the  advance  in  knowledge  about  them  has 
gone  on  with  ever  increasing  rapidity. 

If  it  is  possible  to  increase  the  power  of  the  micro- 
scope or  to  so  train  the  human  eye  that  it  may  see 
more  than  is  seen  at  present,  would  greater  wonders 
be  revealed?  Such  a  possibility  is  ever  before  the  en- 
thusiastic student. 

About  twenty  years  after  Pasteur,  Robert  Koch  de- 
clared that  he  believed  bacteria  were  the  cause  of  dis- 
ease and  not  the  effect,  as  many  had  thought  them  to 
be.  He  began  to  grow  bacteria  on  potatoes  and  in 
other  ways  then  new,  but  now  common.  These  are 
known  as  "solid  cultures." 

This  was  a  great  advance  toward  the  discovery  of 
disease  germs,  because  by  the  differences  in  their  be- 
havior or  growth  on  different  substances  it  was  pos- 
sible to  separate  the  species. 

The  farmer  knows  that  the  same  soil  is  not  equally 
good  for  corn  and  melons  and  that  a  pine  tree  will 
flourish  where  a  willow  would  die.  These  are  at  the 
other  extreme  in  the  plant  world  from  the  invisible 
bacteria,  but  the  microscopic  forms  have  their  prefer- 
ences in  food  and  their  favorable  and  unfavorable 
conditions,  as  well  as  their  well-known  giant  brothers. 


Work  of 
Pasteur 


Koch's 
Theory 


H2  HOUSEHOLD  BACTERIOLOGY 

Method  By  finding  what  they  grow  on  and  their  behavior  in 
of  study  different  SQ\\B .  what  they  like  best  to  eat ;  what  tem- 
perature is  most  favorable  to  reproduction ;  adding  to 
this  the  knowledge  of  structure,  motion,  and  form 
which  the  microscope  reveals,  and  lastly  by  chemical 
analysis  of  the  substances  produced  by  them  during 
growth  the  species  are  determined. 

These  methods  have  also  made  possible  the  cultiva- 
tion of  pure  cultures  which  are  highly  desirable  with 
all  species  of  commercial  value.  A  pure  yeast  makes 
possible  a  saving  of  thousands  of  dollars  in  the  brew- 
ing industries  alone,  and  some  time,  let  us  hope,  the 
housewife  may  be  able  to  buy  pure  yeast  for  her  bread- 
making. 

Bacteria         It  was  not  until   1850  that  these  organisms  were 
»sCpiants     studied  as  plants.    Dr.  Waldo  Burnett,  a  young  phys- 
ician of  Boston,  suggested  this  and  related  theories, 
which  since  his  death  have  been  proved. 

Ten  years  after,  these  forms  were  accepted  and 
classified  by  botanists. 

Founding  There  were  many  observers  and  experimenters  in 
the  field  and  about  1881  the  science  of  Bacteriology 
was  founded.  To  Louis  Pasteur  must  be  ascribed  the 
honor  of  laying  its  corner-stone,  for  he  first  endeav- 
ored to  cultivate  bacteria  and  yeasts  and  tried  to  make 
pure  cultures.  Upon  the  foundation  thus  laid  Robert 
Koch  built  the  germ  theory  of  disease.  He  culti- 
vated certain  germs  and  introducing  them  into  the 
bodies  of  certain  animals  was  able  to  produce  certain 
diseases.  He  then  suggested  the  four  rules  which  still 


HISTORY   OF  BACTERIOLOGY  113 

govern  all  those  who  set  out  on  the  search  for  the 
germ  of  any  particular  disease: 

First,  the  germ  found  in  any  disease  must  be  found     identifying 
in  every  case  of  that  disease.  Genus6 

Second,  this  germ  must  be  grown  artificially  out- 
side the  diseased  body. 

Third,  this  artificial  culture  must  produce  the  spe- 
cific disease  in  the  body  of  a  healthy  animal  when  in- 
oculated into  it. 

Fourth,  the  same  species  found  in  the  original  case 
must  be  found  in  the  case  due  to  inoculation. 

*The  discovery  of  the  bacillus  of  Tuberculosis,  of 
Asiatic  Cholera,  and  of  Typhoid  Fever  followed  in 
rapid  succession.  The  last  fifteen  years  have  been 
crowded  with  searching  investigations  and  numerous 
brilliant  discoveries. 

The  debt  of  the  world  to  these  discoverers  is  in  im- 
portance second  only  to  that  which  it  owes  to  the  bac- 
teria, the  molds,  and  the  yeasts.  Because  the  micro- 
organisms have  been  studied  so  much  from  the  stand- 
point of  disease,  both  in  food  substances  and  man,  their 
beneficent  role  is  often  unappreciated. 

SUMMARY 

From  the  preceding  pages  may  be  gathered  suffi- 
cient information  to  increase  the  appreciation  of  the 
housewife  for  her  many  friends  among  these  micro- 
scopic plants — bacteria,  molds,  yeasts — and  to  put  her 
on  her  guard  against 'the  many  that  under  certain  con- 
ditions, which  she  can  largely  control,  will  .spoil  her 


114  HOUSEHOLD  BACTERIOLOGY 

possessions  or  the  few  that  may  bring  disease  to  her 
family. 
Dust  a»         In  general  the  harmful  bacteria  and  other  forms  are 

of  Danger  brought  into  her  house  as  dust,  which  through  some- 
body's ignorance  or  criminal  carelessness,  is  allowed 
to  scatter  itself;  dust  allowed  to  collect  in  dark  warm 
places,  to  be  blown  about  by  wind;  dust  rising  from 
dried  expectorated  matter  on  sidewalks,  floors  or  fab- 
rics, from  drainage  infected  soil,  possibly  carried  to 
the  water  or  food  supplies. 

It  used  to  be  said  that  dirt  was  matter  in  the  wrong 
place.  We  see  now  that  dangerous  dirt  is  simply  a 
certain  kind  of  matter  in  the  wrong  place.  It  is  in- 
deed, filth,  because  this  dirt  is  alive  it  must  not  be 
allowed  to  grow  under  any  conditions  which  may  bring 
harm  to  man. 

summary         ^  summary  of  a  few  special  terms  explained  in  the 

t6xt  may  Serve  aS  a  review. 

Fermentation  from  a  physiological  standpoint  is  the 
result  of  growth  in  organic  matter  of  a  living  organ- 
ized ferment. 

Alcoholic  fermentation  is  usually  brought  about  by 
yeasts.  A  few  bacteria  and  molds  are  found  to  be 
capable  of  making  weak  alcoholic  solutions. 

Fermentation  is  applied  to  the  process  when ,  the 
products  are  desirable  or  agreeable  and  non-poisonous. 

Putrefaction  is  fermentation  carried  so  far  or  under 
such  conditions  that  the  products  are  undesirable,  dis- 
agreeable, foul  smelling  and  poisonous. 


SUMMARY  115 

It  is  fermentation  of  substances  containing  nitrogen 
— putrid  fermentation. 

The  products  of  these  fermentative  changes  are 
gases  which  give  odors;  acids — lactic,  acetic  and  bu- 
tyric; weak  alcohol,  occasionally,  and  ptomaines 
which,  when  poisonous,  are  called  toxines. 

When  putrefaction  has  ended  and  the  disagreeable     Decay 
products  have  disappeared,  the  residue  is  usually  harm- 
less and  inoffensive.    If  the  processes  of  decomposition 
go  on  in  an  abundance  of  oxygen,  decay  is  usually 
reached  without  offensive  products. 

Sterilization  is  the  removal  of  all  life  and  is  effected 
by  steam,  dry  heat,  chemicals,  or  filtration. 

To  remove  bacteria,  air  may  be  filtered  through  cot- 
ton wool  and  liquids  through  unglazed  clay  or  similar 
substances. 

An  antiseptic  retards  or  prevents  growth.  A  dis- 
infectant kills. 

Some  substances  are  antiseptic  or  disinfectant  ac- 
cording to  their  strength  or  the  conditions  under 
which  they  act.  Sunshine  is  Nature's  free  disin- 
fectant; light  is  commonly  an  antiseptic,  and  may  be 
a  disinfectant.  Dryness,  excess  of  moisture,  salt, 
strong  acids,  the  essential  oils,  soap,  hot  water,  etc., 
may  be  antiseptic  with  some  species  and  disinfectants 
with  others. 

Pasteurization,  chiefly  applied  to  milk  and  cream, 
is  a  process  for  killing  certain  germs  which  cannot 
endure  the  temperature  of  155°  to  165°  F.  for  twenty 


ii6  HOUSEHOLD  BACTERIOLOGY 

minutes.  This  destroys  the  pathogenic  and  lactic  acid 
bacteria.  The  milk  is  then  safe,  that  is,  does  not  carry 
disease  germs,  and  will  keep  longer  than  ordinary 
milk,  but  will  in  time  sour  because  other  germs  gain 
access  to  it. 

Properly  Pasteurized  milk  retains  the  natural  flavor 
and  its  digestibility  is  more  nearly  normal  than  that 
of  milk  which  has  been  sterilized. 

spores  Because  certain  species  of  bacteria  form  spores 
which  are  very  resistant  to  the  ordinary  methods  of 
sterilization,  it  is  necessary  to  repeat  the  process  to 
ensure  success.  This  repeated  boiling  for  three  suc- 
cessive days  is  known  as  Intermittent  Sterilization. 
Dust  Infected  material  which  would  be  harmed  by  thor- 
ough sterilization  should  be  destroyed  by  fire  when- 
ever possible.  It  should  never  be  allowed  to  become 
dry  and  thereby  add  its  infectious  matter  to  dust. 


The  experiments  outlined  in  the  text  should  be  per- 
formed as  far  as  possible.  The  whole  lesson  will  be 
far  more  interesting  if  observation  of  them  precedes 
the  book  study. 

The  questions  should  stimulate  the  application  of 
all  principles  suggested  in  the  text  and,  wherever  pos- 
sible, be  answered  after  actual  observation  of  practice 
based  on  those  principles. 

A  further  knowledge  of  the  whole  subject  of  the 
micro-organisms  included  in  the  science  of  bacteriol- 
ogy may  be  gained  by  reading  the  small  but  interesting 
books  named  in  the  bibliography. 


TEST  QUESTIONS 

The  following  questions  constitute  the  "written  reci- 
tation" which  the  regular  members  of  the  A.  S.  H.  E. 
answer  in  writing  and  send  in  for  the  correction  and 
comment  of  the  instructor.  They  are  intended  to 
emphasize  and  fix  in  the  memory  the  most  important 
points  in  the  lesson. 


EXTRACTS    FROM    THE    INSTRUCTOR'S    NOTE    BOOK 

By  S.  Maria  Elliott, 
Simmons  College,   Boston. 

Education  is  not  knowledge  alone.  It  is  the  de- 
velopment of  the  individual,  and  this  development 
should  make  each  person  a  force  in  the  world.  No 
one  has  a  right  to  keep  for  himself  alone  that  which 
another  needs.  This  is  pre-eminently  true  in  the  line 
of  scientific  education.  If  the  material  side  of  life 
rests  upon  the  principles  of  natural  science,  then  the 
knowledge  of  these  principles  should,  as  soon  as  ac- 
quired, be  put  into  practice  for  our  own  good.  But 
this  alone  is  selfishness.  It  gives  us  power,  but  power 
wrongly  applied  to  ignoble  uses  works  havoc.  Put 
any  newly  acquired  knowledge  into  practical  use  for 
the  benefit  of  humanity  and  the  world  is  improved, 
while  our  own  lives  are  enriched.  In  this  way,  there 
is  a  subtle  truth  in  someone's  definition  of  a  scientist: 
"The  man  who  thinks  God's  thoughts  after  Him." 

Our  school  of  Home  Economics  has  enrolled  among 
students  persons  from  the  Atlantic  to  the  Pacific,  from 
Texas  to  Canada,  and  even  from  far-off  Hungary. 
Some  have  the  schooling  of  the  grammar  grades 
alone,  others  are  in  or  have  passed  through  colleges 
and  even  professional  schools.  Each  has  had  a  dif- 
ferent experience  from  every  other  and  each  may  learn 
from  his  neighbor.  . 

117 


ii8  HOUSEHOLD  BACTERIOLOGY 

The  young  girl  in  the  Tennessee  mountains  may  be 
able  to  give  of  her  experience  to  the  college  profes- 
sor, while  in  between  and  among  all  grades  a  common 
bond  of  interest  has  been  welded  because  of  our  com- 
mon studies. 

Nor  does  the  enrolled  student  alone  gain  knowledge 
from  this  company  of  common  workers.  The  in- 
structors are  not  barred  out  from  this  feast  of  good 
things.  Through  the  tests,  returned  from  all  quarters 
and  by  so  many  persons  of  varied  attainments,  stand- 
ards of  living  and  rich  experiences,  the  instructors  are 
helped  to  a  broader  outlook  and  if,  originally  they 
were  able  to  write  facts  which  might  serve  as  guide- 
posts  in  daily  living,  by  this  time  the  index  finger 
should  assuredly  be  pointed  toward  many  other  helpful 
paths. 

Some  one  has  said  that  a  guide-post  is  that  which 
tells  others  to  go  the  way  in  which  you  will  not  walk. 
This  we  will  not  accept,  but  wherever  any  guiding 
finger  seems  to  invite,  let  us  take  that  path  so  far  at 
least  as  it  serves  our  purpose  and  conditions. 

Here  are  some  of  the  directions  in  which  the  stu- 
dents of  Bacteriology  have  walked  and  others  may 
follow.  The  following  report  from  Utah  may  inspire 
another  to  do  likewise : 

"I  have  tried  to  put  my  newly  acquired  knowledge 
into  practice  around  the  home.  For  example,  I  am 
being  more  careful  of  our  food  products  to  keep  them 
from  dust.  I  have  used  a  dampened  cloth  in  dusting 


NOTES  ug 

and  have  tried  to  impress  upon  my  mind  in  practical 
ways  the  principles  of  action  of  these  three  classes  of 
micro-organisms." 

Definitions  are  said  not  to  define,  but  who  can  im- 
prove upon  this  one  from  Kentucky?  An  infectious 
disease  is  "a  disease  which  is  contracted  from  disease 
germs  which  make  a  specialty  of  this  work,"  and  this 
is  as  true  to  facts,  although  more  difficult  to  read 
aloud,  "Bacteria  are  infinitely  small,  intensely  ener- 
getic, enormously  prolific  protoplasmic  micro-organ- 
isms." 

A  little  knowledge  is  not  always  a  dangerous  thing. 
One  woman  says,  "I  thought  when  I  took  up  the  first 
lesson  paper  that  there  was  nothing  in  it  I  should  ever 
understand,  but  now  it  looks  so  different."  She  had 
seen  molds  through  a  magnifying  glass,  and  goes  on 
to  say,  "At  any  other  time  I  wouldn't  have  given  it  a 
look  or  thought." 

A  guide-post  which  points  decidedly  in  the  direction 
of  success  reads'. 

"Thank  you  more  than  I  can  say  for  the  severity  of 
your  criticisms  on  the  answers  I  sent.  I  liked  it  and 
because  of  it  feel  more  confidence  in  the  whole  course." 

From  Ohio  comes  this  report :  "I  did  find  a  doctor 
in  our  town  who  ...  .  helped  me  to  see  things. 

"I  had  an  idea  that  the  contents  of  the  Petri  dish 
might  be  viewed  at  once.  .  .  .  The  doctor  said 
"Yes,  under  the  focus  it  would  be  as  large  as  the  state 
of  Ohio." 


120  HOUSEHOLD  BACTERIOLOGY 

Perhaps  there  are  other  doctors  in  other  towns  who 
would  be  glad  to  help  the  people  "to  see  things." 

Some  inquiring  minds  met  difficulties,  however,  in 
unexpected  places.  A  student  who  was  "as  thirsty 
after  information  as  ever"  was  discouraged  for  the 
time  being  by  the  fact  that  she  had  borrowed  a  micro- 
scope' from  a  physician  who  was  not  recognized  by  the 
"regulars."  The  city  bacteriologist  who  had  promised 
to  furnish  "microbes"  for  examination  under  said  mi- 
croscope refused  "because  the  Board  of  Health 
wouldn't  like  it,"  if  their  cultures  were  used  by  a 
physician -"who  advertised." 

Disinfection  needs  no  further  explanation  to  one 
who  has  before  her  the  picture  which  she  describes  in 
this  way :  "Some  years  ago  while  traveling  in  Mexico 
we  had  occasion  to  pass  through  a  yellow  fever  dis- 
trict. Fearing  that  the  disease  germs  might  contam- 
inate the  oranges  peddled  at  the  station  by  the  Mex- 
icans and  of  which  we  wished  to  purchase,  a  member 
of  the  party  sterilized  the  fruit  on  the  outside  by  dip- 
ping them  in  alcohol  and  burning  it  off  immediately." 
That  yellow  fever  is  transmitted  only  by  the  sting  of  a 
certain  species  of  mosquito  was  not  then  proved.  That 
there  may  have  been  other  germs  on  the  fruit  is  not  at 
all  unlikely  and  while  the  alcohol  bath  may  have  been 
sufficient,  the  fire  was  certainly  an  ingeniously  sure 
method  of  sterilization. 

A  practicing  physician  among  the  students  says  that 
she  "wishes  every  wife,  mother  and  home-maker  could 


NOTES  121 

and  would  have  the  advantage  of  this  course  of  study. 
Scarcely  an  hour  passes  in  the  day  when  the  prac- 
tical importance  of  the  lessons  is  not  brought  to  my 
mind." 

Having  gained  an  insight  into  the  value  of  the  study 
of  chemistry  and  cleaning,  a  good  Samaritan  was 
anxious  to  help  others  and  used  her  influence  to  have 
valuable  books  on  such  subjects  added  to  the  town 
library. 

A  wail  comes  sounding  from  Georgia:  "The 
housekeeper's  life  is  one  round  of  activity  here  not 
only  on  account  of  the  invisible  pests,  but  those  we 
can  see,  such  as  roaches,  weevils,  etc.  These  may 
abound  in  the  north  in  the  eastern  part,  but  we  never 
saw  one  in  Montana."  Happy  residents  of  Montana 
if  they  have  no  visible  pests,  but  we  have  not  yet 
heard  that  in  Montana  bacteria  are  absent. 

Mrs.  W.  finds  that  strawberries  and  raspberrries  put 
up  uncooked  "kept  perfectly  well  so  far  as  (yeast) 
fermentation  was  concerned."  They  molded  but  only 
on  the  surface.  When  this  surface  growth  was  care- 
fully removed,  there  was  no  taint  present. 

From  the  deck  of  a  houseboat  on  the  Mississippi,  in 
the  midst  of  a  cruise  of  1,200  miles,  comes  the  state- 
ment that  there  bacteria  die,  "for  even  the  dirt  aboard 
exercises  too  much  to  settle  down  to  idleness  and  mis- 
chief." Fresh  air  and  sunshine — Nature's  best  disin- 
fectants— should  certainly  be  found  on  such  a  vacation 
trip. 


122  HOUSEHOLD  BACTERIOLOGY 

An  interested  man  adds  the  bit  of  information  which 
may  inspire  others  to  experiment,  possibly  with  success. 
He  says  they  "have  often — in  Kansas — tried  to  pre- 
serve figs  by  canning  them  but  thus  far  we  have  failed. 
Had  to  preserve  them  in  sugar." 

An  affirmative  answer  must  certainly  be  given  to 
the  pertinent  question:  "Do  not  tooth  brushes  and 
wash  cloths  contain  microbes?"  They  certainly  do 
unless  carefully  cleaned.  The  former  should  occasion- 
ally have  a  bath  in  borax  water.  The  latter  should  be 
well  dried  daily  in  the  sunshine,  if  possible,  and  fre- 
quently boiled.  There  need  not  and  should  not  be  the 
putrid  brush  and  the  sour  cloth.  The  sponge  is  a  very 
difficult  article 'to  keep  sweet  and  clean  by  common 
methods.  The  cloth  is  certainly  much  to  be  preferred 
from  the  standpoint  of  cleanness. 

The  suggestion  is  not  a  bad  one  that  "gloves  be 
worn  always  while  shopping."  We  may  suggest  that 
these  gloves  might  well  be  washable. 

How  much  healthier  our  homes  would  be  if  we 
would  take  the  advice  of  Mrs.  W.  and  "do  away-  with 
the  unnecessary  ornaments,  merely  dust  collectors 
.  .  .  .  dispose  of  them  and  train  the  eye  to  sim- 
plicity and  healthful  emptiness."  Along  the  same  line 
is  Miss  G's  decision:  "I  have  been  very  much 
tempted  of  late  to  give  up  my  rugs  and  mattings  and 
use  carpets,  but  I  feel  now  that  it  would  be  taking  a 
backward  step."  It  would  be  better,  if  it  were  pos- 
sible, to  do  away  with  the  matting  which  unless  the 


NOTES  123 

dust  be  wiped  off  from  the  surface  instead  of  pushed 
through  with  the  broom,  will  store  much  dust  under- 
neath. 

Miss  R.  of  Illinois  has  learned  that  one  element  in 
"vital  resistance"  is  to  keep  one's  self  in  good  health, 
"for  then  my  tonsilitis  germs  wouldn't  have  de- 
veloped." This  is  her  decision  after  having  spent  a 
part  of  the  "Glorious  Fourth"  in  bed  in  the  study  of 
Part  II. 

One  of  our  students  in  Michigan  has  experimented 
in  the  sterilization  and  canning  of  milk,  "using  a  solu- 
tion of  salt  to  increase  the  temperature  of  the  water." 
She  found  that  by  repeating  this  process  three  succes- 
sive days  the  milk  would  and  did  "keep  over  three 
years  and  would  have  kept  indefinitely  except  for  an 
accident." 

An  enthusiastic  teacher  from  Canada  who  "enjoys 
bacteriology  heartily,"  performed  not  only  the  expe- 
riments with  dust  gardens  but  also  numerous  others, 
with  most  satisfactory  results.  Her  enthusiasm  and 
success  may  well  be  passed  along  for  the  benefit  of 
others. 

One  of  her  best  results  in  growing  molds  came  from 
a  medium  of  ten  per  cent  prune  juice,  ten  per  cent 
gelatine  with  eighty  per  cent  water.  This  was  ex- 
posed for  twenty  minutes.  In  a  week  there  had 
grown  "about  twenty  mold  colonies"  and  five  of 
bacteria. 

Another  garden  was  made  like  the  above,  substitut- 


124  HOUSEHOLD  BACTERIOLOGY 

ing  jelly  for  the  juice.  In  this  the  bacteria  flourished 
better  than  the  molds.  One  of  the  gardens  which  she 
tried  was  turned  to  liquid  in  a  week. 

She  was  fortunate  to  receive  from  a  bacteriologist  a 
pure  culture  of  b.  prodigiosus  or  the  "miracle  germ." 
This  she  planted  in  the  yolk  of  a  hard-boiled  egg  and 
in  a  week  it  had  transformed  the  yolk  to  a  red  mass 
mingled  with  much  liquid.  This  was  well  covered  and 
kept  in  darkness.  She  one  day  found  that  the  hecto- 
graph had  become  a  garden  of  molds  and  bacteria. 
Under  the  right  conditions  it  might  have  been  lique- 
fied. 

That  childen  can  be  readily  taught  by  observation 
is  shown  by  a  report  from  the  same  teacher.  A  girl 
insisted  that  her  hands  were  clean,  but  a  tablespoon 
of  the  water  in  which  she  washed  her  clean  hands 
when  introduced  into  milk  proved  an  efficient  aid  in  its 
putrefaction.  "The  cooking  class  never  forgot  to 
wash  their  hands." 

A  class  of  farmers'  daughters  found  many  sugges- 
tions for  their  future  care  of  milk  products  from  va- 
rious experiments  in  the  cultivation  in  milk  of  the  dif- 
ferent species  which  turn  it  sour,  putrid,  bitter,  etc. 

Such  reports  as  these  should  stimulate  other  teach- 
ers to  interest,  to  instruct,  to  educate,  by  similar  ex- 
periments, the  children  under  their  care.  Anything 
which  will  raise  the  standard  of  personal  cleanness  or 
that  of  food  supplies  and  general  house  conditions  will 
tend  toward  health  and  greater  economy. 


NOTES  125 

And  so  the  tests  and  personal  letters  continue  to 
encourage  the  instructor  and  open  up  many  a  vista  of 
unexpected  applications  or  suggested  truths. 

The  variety  of  questions  show  the  great  need  of  the 
study  even  among  those  favored  with  high  scholarship 
as  well  as  among  those  trained  in  the  thorough  but 
slower  school  of  experience. 

When  many  facts  of  everyday  life,  of  common  ob- 
servation, are  seen  to  be  caused  by  the  growth  of  omni- 
present, invisible  plants  put  into  Lhe  world  as  benef- 
icent agents,  all  life  becomes  more  interesting.  Such 
study  should  lead  away  from  foolish  or  ungrounded 
fear.  It  should  lead  to  thought  and  wise  action,  that 
the  danger  spots  be  prevented  or  removed;  that  each 
do  all  in  his  power  to  protect  not  only  himself  but  his 
neighbor. 

How  strongly  it  emphasizes  the  truth  from  the  great 
poet-philosopher,  John  Milton: 

"  Not  to  know  at  large 
Of  things  remote  from  use, 
But  to  know  that  which 
Before  us  lies  in  daily  life 
Is  tne  prime  wisdom." 


SAFEGUARDS  OF  THE  BODY  AGAINST  DISEASE* 

By  T.  Mitchell  Prudden. 

Author   of  "Dust  and  Its   Dangers,"   "The   Story  of  the 
Bacteria,"  etc.,  etc. 

Among  the  shibboleths  of  physicians  one  of  the 
more  recent  and  perhaps  the  most  widely  popular  to- 
day is  the  word  immunity,  relating  to  infectious  or 
bacterial  disease.  The  subject  holds  the  floor  in  the 
learned  societies ;  it  crams  the  medical  books  and  jour- 
nals; it  lures  the  solitary  workers  in  the  laboratories 
to  long  and  toilsome  quests.  At  last  the  layman  has 
begun  the  query  as  to  what  it  is  all  about,  and  how 
the  new  lore  which  filters  through  the  magazines  and 
newspapers  out  to  him  may  affect  his  chance  for  the 
healthful  threescore  years  and  ten  which  is  his  birth- 
right, but  of  which  he  is  too  often  ruthlessly  deprived. 

It  is  really  worth  while  for  everybody  to  know 
something  about  immunity  to  infectious  diseases.  For 
the  new  doctrines  and  their  practical  applications  in 
the  workaday  world  are  full  of  promise  for  the  preven- 
tion and  cure  of  the  infectious  maladies,  if  only  the 
public  will  bear  its  part  with  intelligence  and  zeal. 

The  beginning  of  the  story  goes  back  more  than  a 
quarter  of  a  century,  when  the  notion  still  lingered  on 
that  disease  was  a  mysterious  something  apart  from 

*Reprinted  from  The  Outlook  by  permission. 
127 


128  HOUSEHOLD  BACTERIOLOGY 

the  body  machine,  which  with  sinister  intent  took  pos- 
session of  our  interiors  and  battled  for  our  lives;  or 
was  a  visitation  of  Providence  about  which  we  might 
not  inquire  too  curiously.  Then  suddenly  we  became 
aware  that  the  soil,  air,  and  water,  the  surfaces  of 
plants  and  of  our  own  bodies  were  swarming  with 
minute,  invisible,  living  beings,  some  few  of  which 
were  of  the  greatest  importance  to  man  because  they 
were  capable  of  inciting  serious  disorders.  By  a  tech- 
nical device  of  the  laboratory  it  was  soon  found  pos^ 
sible  to  secure  these  invisible  plants  from  their  various 
sources,  to  separate  them  one  from  another,  and  to 
cultivate  and  study  them  with  as  much  precision  as  the 
farmer  grows  and  gathers  his  various  crops. 

Of  course  at  first  the  few  harmful  members  of  this 
newly  exploited  group  of  living  things  cast  a  shadow 
over  all  the  rest.  And  we  shuddered  as  the  pioneer  in 
this  new  domain  of  science  revealed  the  thousands 
and  tens  of  thousands  of  bacteria  which  we  might  be 
swallowing  with  our  glass  of  water  or  with  our  bunch 
of  grapes.  But  we  were  soon  reassured,  for  we  were 
told  that  we  had  nothing  to  fear  from  the  rank  and 
file  of  our  humble,  newly  discovered  commensals ;  that, 
on  the  contrary,  they  were  our  friends,  without  which, 
indeed,  the  world  of  life  could  not  long  continue.  It 
was  only  the  few  which  we  must  avoid  if  we  would 
steer  clear  of  tuberculosis,  pneumonia,  diphtheria,  ty- 
phoid fever,  cholera,  and  a  dozen  or  so  others  of  the 
uncanny  brood  of  infectious  diseases. 


NOTES  129 

These  disease-producing  germs  the  bacteriologist 
soon  came  to  know  very  well  as  he  grew  them  in  the 
safe  purlieus  of  his  laboratories  and  found  out  the 
various  ways  in  which  they  were  able  to  work  havoc 
in  the  delicate  mechanism  of  their  earth-neighbor, 
man.  Thus  the  nature  of  disease  became  clearer  and 
the  problems  of  its  prevention  and  cure  definite  and 
precise. 

BARRIERS   OF   THE  BODY. 

The  healthy  human  body  is  safe-guarded  in  many 
effective  ways  against  the  entrance  and  continued  life 
of  bacteria  and  allied  organisms.  The  tough  skin 
affords  a  most  impregnable  barrier.  The  nose  and 
throat  and  the  tubes  leading  to  the  lungs  are  protected 
with  various  mechanisms  barring  the  way  to  many 
germs  which  dusty  air  bears  in  every  breath.  The 
complex  chemical  processes  in  our  digestive  apparatus 
which  convert  our  food  into  building  material  for 
brain  and  muscle  spell  death  to  the  myriads  of  bac- 
teria with  which  our  uncooked  foods  are  mingled.  So. 
altogether,  our  life  among  bacteria,  even  those  of  the 
deadly  sort,  is  usually  exposed  to  little  hazard. 

But  when  the  best  is  said,  these  minute  inciters  of 
disease  do  now  and  then  win  their  way  to  the  intimate 
recesses  of  our  bodies,  producing  serious  results.  The 
measure  of  their  ravages  is  found  in  the  tables  of  the 
statisticians,  which  show  that  a  large  proportion  of 
all  who  die  fall  victims  to  these  invisible  foes,  and 
that,  too,  at  an  age  when  life  holds  out  its  brightest 
promise. 


130  HOUSEHOLD  BACTERIOLOGY 

Now  let  us  see  how  these  germs  are  able  to  do  such 
serious  damage  in  the  living  body.  This  body  is 
made  up  of  a  bony  framework,  around  which  various 
tissues  and  organs  are  securely  and  compactly  grouped. 
Each  one  of  these  tissues  and  organs  is  composed  of 
tiny  structures  called  cells.  The  cells  are  little  centers 
of  energy  stored  up  from  the  food  we  eat  and  the  air 
we  breathe — little  laboratories  in  which  chemical  pro- 
cesses of  the  most  subtle  character  are  constantly  go- 
ing on.  And  the  life  of  the  body  is  simply  the  sum 
of  the  more  or  less  independent  but  co-ordinated  lives 
of  the  cells  which  compose  it,  all  acting  in  har- 
mony. *  *  * 

All  these  delicate  and  exquisitely  adjusted  elements 
of  the  body  are  able  to  adapt  themselves  to  many 
vicissitudes  without  serious  disturbance  to  that  sensi- 
tive equilibrium  which  we  name  health.  We  may 
starve  them,  surfeit  them,  overwork  them,  and  poison 
them  in  the  most  abandoned  fashion.  But  they  sway 
back  to  their  respective  tasks  again  when  our  abuse 
ceases.  Unless  we  go  too  far ;  and  then  they  may 
struggle  on,  but  only  in  the  halting,  perverted  way 
which  we  call  disease. 

Now,  what  happens  when  into  this  happy  family  of 
cells,  each  nicely  adjusted  to  the  others,  and  all  en- 
gaged in  their  various  tasks,  living  bacteria  enter,  hav- 
ing escaped  the  outer  safeguards  ? 

But  before  we  try  to  discover  this,  let  us  brush 
away  a  few  cobwebs. 


SAFEGUARDS  OF  THE  BODY  131 

NATURE  OF   DISEASE 

We  are  so  accustomed  to  personify  disease,  to  think 
of  it  as  a  visitation  of  malign  forces,  and  to  talk  of  it 
in  terms  which  belong  in  the  era  of  superstition  and 
personal  devils,  that  clear  notions  of  disease  as  a 
process,  not  a  thing,  are  rare  indeed. 

Disease  is  a  perverted  process  of  the  living  body 
cells.  Bacteria  are  not  the  disease;  they  are  only  the 
inciters  of  disease;  nor  do  they  enter  the  body  with 
sinister  intent.  If  the  chances  of  the  hour  bring  them 
to  rest  among  the  living  body  cells,  and  if  the  condi- 
tions are  favorable,  they  begin  to  grow,  but  with  just 
as  little  purpose  for  good  or  evil  as  if  they  had  lodged 
upon  the  surface  of  a  rotten  turnip. 

Many  of  the  bacteria  which -enter  the  body  do  not 
grow  at  all.  The  soil  is  not  to  their  liking,  the  envi- 
ronment is  not  congenial;  they  die  and  are  hustled 
off  forthwith  by  certain  lowly  organized  cells — phago- 
cytes we  call  them — which  are  the  scavengers  of  the 
body,  and  are  ever  moving  here  and  there  to  keep  the 
tissues  clear  and  clean.  Many  bacteria,  on  the  other 
hand,  find  in  the  living  body  conditions  suitable  enough, 
faute  de  mieux,  for  their  simple  life  processes.  But 
they  are  speedily  devoured  and  digested  by  the  scaven- 
ger cells,  or  are  killed  by  destructive  body  juices,  and 
so  their  tragedies  end. 

But  there  is  another  side  to  the  story  when  the  bac- 
teria which  are  stranded  within  the  tissues  are  not 
to  be  tolerated  in  a  well-organized  cell  family.  Then 
trouble  begins. 


132  HOUSEHOLD  BACTERIOLOGY 

We  are  likely  to  think  that  because  bacteria  are  so 
small  and  lowly  they  cannot  do  much.  But  in  fact 
they  do  a  great  deal.  Their  life  processes  are  ex- 
tremely complex.  They  are  chemical  engines  of  great 
potency.  Out  of  the  food  which  they  assimilate  they 
manufacture  a  host  of  subtle  poisons,  some  of  which 
are  stored  up  in  their  tiny  bodies,  some  set  free  into 
the  fluids  of  their  hosts.  This,  in  fact,  is  the  front  of 
their  offending:  the  poisons  which  they  elaborate  and 
set  free  damage  the  cells. 

Sometimes  these  poisons  interfere  with  the  neces- 
sary performances  of  the  cells  close  about  them,  or  they 
harm  them,  but  not  irretrievably;  or  they  may  kill 
them  forthwith.  Again,  they  are  carried  far  and  wide 
throughout  the  body,  and  the  heart  is  enfeebled,  the 
brain  palsied,  or  fever  dominates  the  scene. 

This  is  the  situation,  then,  when  disease-producing 
bacteria  get  in  among  the  living  body  cells  and  begin 
to  grow,  setting  free  their  powerful  poisons.  It  is 
cell  against  cell — the  well-bred,  highly  differentiated 
cell  of  the  body  against  the  crude,  prolific  spark  of 
matter  way  down  upon  her  borderland  of  life,  potent 
only  to  eat,  to  multiply,  to  shed  abroad  its  poison.  But 
the  weapons  of  both  the  combatants  are  poisonous. 
For  we  should  not  permit  our  sympathetic  viewpoint 
to  obscure  the  fact  that  the  fluids  and  the  digestive 
juices  which  our  own  cells  elaborate  are  poisons  for 
bacteria,  quite  as  much  as  is  their  stuff  for  us.  It  is 
the  old  story  of  the  survival  of  the  fittest  here  in  this 


SAFEGUARDS  OF  THE  BODY  133 

little  hidden  arena.  A  new  environment  is  estab- 
lished both  for  the  body  cells  and  for  the  bacteria ;  and 
what  we  dramatize  as  a  battle  is  really  only  the  at- 
tempt of  each  to  adapt  itself  to  the  new  conditions 
furnished  by  the  other.  The  one  which  adapts  itself 
most  readily  and  completely  and  quickly  wins,  by 
survival. 

Infectious  diseases,  then,  are  those  which  are  in- 
duced by  the  entrance  into  the  body  and  the  multipli- 
cation there  of  disease-inducing  micro-organisms. 
These  are  most  frequently  bacteria;  but  other  lowly 
beings,  such  as  yeasts  and  minute  animals  called  pro- 
tozoa, are  sometimes  to  blame.  Each  of  these  infec- 
tious diseases  has  its  peculiar  characteristics  by  which 
physicians  recognize  it.  These  features  are  especially 
dependent  upon  the  nature  of  the  bacteria  which  in- 
duce them :  their  ways  of  growing,  the  nature  of-  the 
poisons  which  .they  set  free,  their  tenacity  of  life,  etc. 
But  the  body  cells  have  their  particular  vulnerabilities 
to  bacterial  poisons,  so  that  in  one  case  it  is  the  nervous 
system,  in  another  the  lungs,  in  another  the  digestive 
apparatus,  which  especially  suffers.  Moreover,  as  one 
rose  is  redder  than  another,  or  one  aromatic  plant 
more  pungent  than  its  fellow,  so  in  one  case  the  bac- 
teria which  gain  access  to  the  body  may  evolve  a 
more  potent  poison  than  in  another,  and  then  the  dis- 
ease may  be  of  a  more  virulent  type.  So  also  an 
individual  may  at  the  time  of  infection  be  much  more 
susceptible  to  the  ravages  of  the  germ  than  is  usual, 
and  thus  the  victim  of  a  graver  form  of  disease. 


134  HOUSEHOLD  BACTERIOLOGY 

Now  we  come  to  immunity.  We  have  seen  that, 
under  the  usual  conditions,  the  body  may  be  capable 
of  disposing  of  bacteria  or  other  microbes  which  enter 
it  by  means  of  its  cells  or  its  fluids,  so  that  the  in- 
vaders can  do  no  harm.  This  condition  is  called  here- 
ditary immunity — an  immunity  which  is  born  with  us. 
There  is  a  good  deal  of  difference  in  animal  species 
in  this  respect.  For  many  bacteria  which  are  deadly 
to  some  of  the  lower  animals  are  harmless  to  man,  and 
vice  versa.  So  also  among  the  lower  animals  them- 
selves some  are  susceptible,  some  not,  to  the  same 
species  of  bacteria. 

But  there  is  another  phase  of  immunity  which  we 
must  look  at  a  little  more  closely,  called  acquired  im- 
munity. It  is  a  very  old  observation  of  the  doctors, 
which  has  become  part  of  the  lore  of  the  layman,  that 
there  are  infectious  diseases  in  which  one  attack,  if 
recovered  from,  protects  its  victim  for  a  longer  or 
shorter  period  against  a  subsequent  attack.  This  is 
true  of  smallpox,  measles,  scarlet  fever  and  in  less 
marked  degree  of  typhoid  fever,  diphtheria  and  others. 

Here  is  a  form  of  acquired  immunity  secured 
through  an  experience  of  the  disease  itself.  In  fact,  re- 
covery from  an  infectious  disease  can  take  place  only 
by  the  establishment  of  an  immunity  which  did  not  pre- 
viou^ly  exist.  .  But  this  acquired  immunity  in  some  in- 
stances suffices  only  for  the  exigencies  of  the  hour, 
while  in  others  it  persists  for  some  time,  precluding 
fresh  infection. 


SAFEGUARDS  OF  THE  BODY  135 

In  order  to  understand  what  has  happened  in  the 
body  of  a  person  who  has  thus  acquired  immunity 
through  a  successfully  weathered  attack  of  an  infec- 
tious disease,  it  will  be  necessary  for  us  to  look  at 
some  very  remarkable  achievements  of  the  past  few 
years  in  the  prevention  and  cure  of  diphtheria.  For, 
though  the  fact  of  immunity  acquired  through  disease 
has  been  known  so  long,  no  one  until  recently  could 
offer  even  a  plausible  conjecture  as  to  the  reason  for  it. 
Among  the  earlier  of  the  disease-inducing  bacteria  to 
be  discovered,  some  twenty  years  ago,  was  the  bacillus 
of  diphtheria.  This  is  a  little  rod-like  plant  found  only 
in  connection  with  this  disease,  or  in  those  who  have 
been  exposed  to  it.  It  is  readily  cultivated  in  the 
laboratory,  being  very  fond  of  beef  tea,  in  which  it  is 
commonly  grown. 

When  a  few  of  these  living  bacilli  from  the  culture 
are  put  beneath  the  skin  of  animals,  such  as  rabbits 
or  guinea  pigs,  a  fatal  disease  is  induced,  essentially 
similar  to  the  disease — diphtheria — in  man. 

In  the  early  days  of  bacteriology  it  was  believed 
that,  in  order  to  induce  artificially  the  symptoms  of 
an  infectious  disease,  the  living  germs  must  be  put 
into  the  body,  and  grow  there.  But  it  was  presently 
discovered  that  if  you  separate  all  the  germs  from  a 
culture  of  the  diphtheria  bacillus,  and  introduce  the 
beef  tea  in  which  they  had  grown  for  some  time,  into 
an  animal,  you  can  induce  the  symptoms  of  the  disease 
just  as  well  as  if  the  germs  themselves  are  put  in. 


136  HOUSEHOLD  BACTERIOLOGY 

Thus  was  revealed  the  significant  fact  that  bacteria 
may  damage  the  body  quite  as  much  by  the  poisons 
which  they  elaborate  as  by  their  direct  presence. 

Now  came  the  next  step  in  the  upbuilding  of  this 
remarkable  series  of  discoveries.  It  was  found  that 
if  this  beef  tea  in  which  diphtheria  bacilli  have  grown, 
and  which  contains  the  germ-poison,  be  introduced 
into  an  animal,  at  first  in  very  minute  quantities,  which 
are  gradually  increased  in  subsequent  doses,  the  ani- 
mal grows  more  and  more  tolerant  of  the  poison,  until 
at  last  he  sustains  with  indifference  amounts  which,  if 
given  at  first,  would  have  been  certainly  and  speedily 
fatal. 

In  other  words,  it  was  found  that  by  the  use  of  the 
poison  alone  of  the  diphtheria  bacillus  in  increasing 
doses,  an  animal  can  be  rendered  artificially  immune 
without  having  s'uffered  from  the  disease  diphtheria 
at  all. 

But  now  a  most  incredible  thing  was  discovered. 
It  was  found  that  if  the  blood  be  drawn  from  an  ani- 
mal thus  rendered  artificially  immune,  and  allowed 
to  clot,  the  yellowish,  watery  fluid  which  separates 
from  the  solid,  part,  and  which  we  call  blood  serum, 
contains  something  which,  when  the  serum  is  intro- 
duced into  the  body  of  another  animal,  perfectly  pro- 
tects him,  not  only  from  the  poison  of  the  diphtheria 
germ,  but  from  the  living  germ  itself ;  in  other  words, 
renders  him,  too,  immune. 


SAFEGUARDS  OF  THE  BODY  137 

ANTITOXIN. 

This  curious  something  so  potent  and  so  beneficent 
was  called  antitoxin,  because  it  acts  by  neutralizing  or 
abolishing  the  harmful  effects  of  the  toxin — that  is, 
the  poison  of  the  diphtheria  germ. 

No  chemist  has  ever  been  able  to  separate  antitoxin 
from  the  blood  serum ;  no  man  knows  its  composition ; 
but  there  it  is,  the  heart,  it  seems,  of  the  mystery  of 
immunity. 

One  might  think  that  we  had  found  here  some  re- 
markable cure-all  in  this  antitoxin,  and  that  it  would 
prevent  or  cure  other  infectious  diseases.  But  this 
is  not  the  case.  It  has  no  more  effect  in  the  preven- 
tion or  cure  of  other  diseases,  such  as  pneumonia, 
typhoid  fever,  etc.,  than  so  much  water.  In  other 
words,  its  action  is  specific. 

The  seeker  of  light  in  fields  relating  to  medicine 
is  rarely  free  from  the  consciousness  of  urgency  in  the 
solution  of  his  problem.  So  the  moment  he  found 
that  he  could  protect  the  lower  animals  against  the 
ravages  of  diphtheria  which  he  had  artificially  induced, 
he  turned  at  once  to  the  possibility  of  human  protec- 
tion and  cure.  And  the  situation  was  indeed  urgent. 
No  disease  was  more  dreaded  than  diphtheria,  espe- 
cially in  children;  the  suffering  of  the  victims  was 
pitiful,  the  mortality  great. 

The  first  experiments  were  made  on  small  animals, 
but  if  the  serum  were  to  be  used  in  children  larger 
quantities  would  be  required,  so  sheep  and  goats  were 


138  HOUSEHOLD  BACTERIOLOGY 

immunized.  But  these  did  not  furnish  enough.  So  at 
last  the  horse  was  tried,  and  was  found  admirably 
adapted  to  the  purpose.  He  lends  himself  readily  to 
the  increasing  doses  of  the  potent  diphtheria  poison ; 
he  is  easily  rendered  immune,  and  he  furnishes  without 
especial  inconvenience  a  large  quantity  of  blood.  In 
fact,  he  makes  no  more  fuss  about  losing  blood  than 
did  the  old  people  along  in  the  early  part  of  the  last 
century,  who  were  quite  accustomed  in  the  springtime, 
when  they  felt  a  bit  heavy  and  had  a  little  headache, 
to  drop  into  the  nearest  barber  shop  to  be  bled. 

The  preparation  of  diphtheria  antitoxin  has  been 
brought  to  a  high  state  of  perfection.  The  horses 
are  first  very  carefully  tested  so  as  to  be  certain  that 
they  have  no  disease.  They  are  well  fed  and  groomed, 
and  suitably  exercised.  At  first  a  small  amount  of  the 
diphtheria  toxin  is  injected  beneath  the  skin.  After 
a  few  days  a  larger  dose  is  given,  and  then  at  intervals 
larger  and  larger  quantities,  until  at  last  the  horse  is 
receiving  such  an  amount  in  a  single  dose  as  if  given 
at  first  would  have  sufficed  to  kill  not  only  one  but 
many  horses.  He  has  not  had  diphtheria  at  all,  but 
he  is  now  poison-proof — immune. 

The  animal  is  then  bled  from  the  large  vein  in  the 
neck,  the  greatest  care  being  taken,  by  cleansing  of  the 
skin,  the  use  of  sterilized  instruments,  etc.,  that  no 
outside  germ  shall  get  into  the  blood  as  it  flows.  This 
blood  is  set  aside  in  a  cool  place,  and  presently,  as  the 
clot  forms,  the  serum  separates  in  considerable  quan- 


SAFEGUARDS  OF  THE  BODY  139 

tity.  This  is  drawn  off  into  flasks  and  contains  the 
precious  life-saving  stuff,  antitoxin. 

Since  no  one  has  been  able  to  separate  this  anti- 
toxic substance  from  the  serum,  it  is  necessary,  in 
order  to  find  out  how  powerful  it  is — for  its  virtue 
varies  with  every  horse — to  have  recourse  to  quite  un- 
usual methods.  It  cannot  be  weighed  as  the  druggist 
weighs  rhubarb  or  camphor.  But  as  its  value  depends 
upon  its  powers  to  neutralize  the  action  of  the  diph- 
theria poison  in  living  animals,  the  test  of  its  strength 
must  be  made  on  these.  Guinea  pigs  are  usually  em- 
ployed. It  is  thus  learned  how  much  of  the  antitoxin 
to  be  tested  is  necessary  to  save  the  life  of  the  animal 
which  has  received  a  fatal  dose  of  the  diphtheria 
poison. 

The  amount  necessary  for  the  protection  of  a  human 
being  is  larger  in  such  proportion  as  his  weight  is 
greater  than  that  of  the  guinea  pig.  The  saving  power 
of  each  specimen  of  antitoxic  horse  serum  having  been 
thus  determined,  it  is  carefully  tested  to  see  that  no 
contamination  has  taken  place,  then  it  is  divided  into 
the  proper  doses,  each  in  a  small  sealed  bottle,  and 
sent  out  upon  its  mission. 

This  antitoxin  is  not  effective  if  given  by  the  mouth, 
as  many  drugs  are ;  but  it  is  introduced  beneath  the 
skin  by  a  small  syringe,  and  is  speedily  absorbed  into 
the  body  fluids. 

Now,  what  has  been  accomplished  by  the  use  of  this 
new  and  curious  form  of  medicine?  The  mortality 


140  HOUSEHOLD  BACTERIOLOGY 

from  diphtheria,  taking  the  results  the  world  over  and 
in  a  general  way,  has  been  reduced  more  than  50  per 
cent,  and,  under  the  most  favorable  conditions,  full 
75  per  cent.  I  need  not  dwell  upon  the  significance  of 
this  beneficent  result  in  the  saving  of  life  and  in  the 
relief  of  suffering. 

But  there  is  another  way  in  which  diphtheria  anti- 
toxin has  been  of  the  greatest  value;  that  is,  in  the 
prevention  of  the  disease  among  those  who  have  been 
exposed  to  infection  in  families,  schools,  and  other  pub- 
lic institutions.  Under  these  conditions  an  injection 
of  the  antitoxin  beneath  the  skin  has  been  the  means 
of  warding  off  an  attack  of  the  disease  in  groups  of 
persons,  some  of  whom  without  it  must  inevitably  have 

We  should  be  most  ungrateful  if  we  failed  to  recog- 
nize the  importance  of  this  new  relationship  which  has 
been  established  between  ourselves  and  our  old  and 
ever-useful  friend,  the  horse.  We  make  him  manu- 
facture for  us  in  the  department  of  his  interior  that 
protective  stuff  which  we  could  otherwise  secure  only 
by  ourselves  sustaining  an  attack  of  diphtheria,  and 
this,  too,  with  the  chances  against  success. 

We  are  now  prepared  to  inquire  how  this  curious 
antitoxin  acts  in  the  body  to  produce  these  truly  mar- 
velous effects.  Has  the  body  kept  secreted  all  through 
these  years  of  evolution  some  special  mechanism,  or 
some  chemical  potency,  by  which  all  of  a  sudden  it 
can  protect  itself  against  so  subtle  and  so  special  a 
poison  as  this  roving  bacillus  ?  And  if  so,  do  we  keep 


SAFEGUARDS  OF  THE  BODY  141 

on  hand  in  our  mysterious  insides  the  latent  power  of 
protection  against  all  the  special  forms  of  disease- 
producing  bacteria  which  wander  the  earth?  How 
does  it  fit  into  physiology?  Or  can  we  indeed  create 
new  protective  powers  in  the  stress  of  such  varied 
accidents  as  new  infections  involve? 

We  have  seen  that  the  diphtheria  bacillus  produces 
its  deadly  effects  through  a  poison  which  it  sets  free 
as  it  grows  in  the  body.  In  order  to  understand  how 
this  poison  is  rendered  harmless,  we  must  know  how 
it  damages  the  delicate  body  cells.  So  we  must  go 
back  to  the  cell  for  a  moment.  These  cells  in  the 
living  body  sit  in  their  respective  places,  and  as  the 
nutrient  fluids  pass  and  bathe  them,  each  of  them 
being  a  powerful  little  chemical  factory,  they  seize  up- 
on whatever  nutrient  molecules  they  require,  and  out 
of  these  build  up  such  new  substances  as  they  need  in 
their  business,  whether  this  be  self-nutrition,  or  the 
storage  of  energy,  or  the  furnishing  of  special  life- 
stuff  for  their  neighbors.  So  each  cell  is  armed  with 
this  power  of  forming  chemical  union  with  the  food. 

But  suppose  something  comes  along  in  the  body 
fluids  with  which  the  cell  can  and  does  form  the  same 
sort  of  chemical  union,  but  which  is  not  a  food;  on 
the  contrary,  damages  the  cell — that  is,  is  poisonous 
or  toxic  for  it.  The  cell  suffers,  of  course — first,  by 
the  direct  damage,  and,  second,  by  the  loss  of  its 
food-securing  capacity.  The  latter  it  has  used  up  in 
uniting  with  the  poison. 


142  HOUSEHOLD  BACTERIOLOGY 

Now,  the  cell — so  runs  the  theory— finding  itself 
deprived  of  its  food,  produces  a  new  and  increased 
amount  of  this  food-seizing  substance.  In  fact,  in 
accordance  with  a  well-known  law  in  pathology,  it 
produces  such  a  surplus  of  this  substance  that  it  is 
cast  off  into  the  body  fluid. 

But  this  food-seizing  substance,  now  produced  in 
superabundance  and  cast  off,  is  still  capable  of  uniting 
with  the  poison  which  is  circulating  in  the  body  fluids. 
This  it  does,  and  as  molecule  by  molecule  the  poison 
forms  the  new  chemical  union  it  is  neutralized  and 
so  prevented  from  coming  in  contact  with  the  cells, 
where  alone  it  can  do  harm.  This  is  antitoxic  im- 
munity. 

Now,  if  more  of  this  stuff  is  given  off  by  the  cells 
in  the  emergency  than  is  necessary  to  render  all  the 
poison  harmless,  the  excess  in  the  body  fluid  remains 
there  as  unused  antitoxin.  This  is  the  condition  of 
the  immuned  horse.  His  cells  have  produced  more 
antitoxin  than  is  necessary  to  protect  himself,  and 
we  draw  off  some  of  it  in  the  blood  and  use  it  to 
save  the  child. 

Thus  we  see  that  this  curious  protective  process 
is  not  an  incredible  anomaly,  but  that  the  body  cells 
have  availed  themselves  in  an  emergency  as  protective 
agencies  of  those  capacities  which  under  normal  con- 
ditions they  use  in  the  assimilation  of  their  food. 

This  power  of  the  body  to  protect  itself  against  the 
poisonous  products  of  bacterial  life  may  be  exerted 


SAFEGUARDS  OF  THE  BODY  143 

in  a  similar  way  in  the  presence  of  other  poisons. 
Thus  certain  poisonous  vegetable  extracts  and  the 
venom  of  snakes  may  be  used  to  secure  artificial  im- 
munity in  the  horse,  with  the  development  of  antitoxin. 
In  countries  where  venomous  reptiles  abound  the  loss 
of  life  from  their  bites  is  sometimes  very  great;  for 
example,  in  India,  where  the  great  cobra  slays  many 
victims.  An  antitoxin  for  snake  poison  is  now  made 
which  is  most  effective  against  the  bites  of  the  cobra 
and  several  other  venomous  serpents.  It  is  called 
antivenin.  Its  efficiency  for  rattlesnake  bites  has  been 
claimed,  but  recent  studies  have  thrown  some  doubt 
upon  this  point. 

Of  course  as  soon  as  this  remarkable  diphtheria 
antitoxin  was  discovered  the  eager  workers  in  the 
field  of  preventive  medicine  at  once  concluded  that  we 
were  at  the  dawn  of  a  new  day.  For  if  we  can  so 
effectively  control  the  ravages  of  diphtheria,  why  not 
of  the  other  bacterial  diseases?  So  everybody  set  to 
work  to  discover  new  antitoxic  sera — of  pneumonia, 
tuberculosis,  plague,  typhoid  fever,  cholera  and  vari- 
ous forms  of  blood  poisoning,  the  bacterial  excitants 
of  which  were  already  known. 

But,  unfortunately,  these  efforts,  pursued  with  the 
utmost  zeal  and  persistence  the  world  over,  have  thus 
far  met  with  very  little  success.  Antitoxic  sera  for 
tetanus,  or  lockjaw,  and  for  some  forms  of  blood 
poisoning,  have  seemed  to  be  measurably  useful.  But, 
for  the  most  part,  the  attempts  have  failed,  except  in 


144  HOUSEHOLD  BACTERIOLOGY 

the  daily  newspaper,  for  which  the  discovery  overnight 
of  a  new  "serum"  seems  to  furnish  an  item  of  per- 
petual interest. 

The  reasons  for  this  failure  are  in  part  evident  to 
experts  in  this  field,  in  part  are  still  very  obscure,  and 
are  too  technical  to  be  entered  upon  here.  But  the 
eager  and  toilsome  search  goes  on  with  such  inspira- 
tion as  is  ever  his  who  deals  with  these  urgent  prob- 
lems of  life  and  death,  and  at  any  moment  the  key  to 
the  riddle  may  lie  in  our  hands. 

It  would  be  interesting,  did  the  scope  of  this  article 
permit,  to  look  at  the  means  by  which  the  body  pro- 
tects itself  against  infection,  not  by  neutralization  of 
poisons,  but  by  the  actual  destruction  of  the  poison 
producers — the  bacteria  themselves.  Suffice  it  to  say 
that  here  also,  in  this  bacteria-destroying  phase  of 
immunity — germicidal  immunity,  it  is  called — the  body 
does  not  command  new  forces  or  mechanisms,  but 
makes  use  of  those  which  are  maintained  for  its  daily 
service,  but  which  in  the  emergency  it  wields  to  new 
ends  and  with  exalted  energy. 

OTHER  METHODS  OF  PROTECTION. 

When  it  was  found  that  it  was  not  possible  at  once 
to  secure  antitoxic  sera  for  other  infectious  diseases 
in  the  way  which  had  been  so  successful  with  diph- 
theria, the  attempt  was  made  to  obtain  protection  in 
some  other  way.  The  leading  idea  in  these  researches 
was  to  find  a  method  of  adapting  man  to  pathogenic 
germs  without  exposing  him  in  the  process  to  the 


VACCINATION  145 

risks  of  the  disease.  Some  bacteria  seem  to  produce 
their  harmful  effects  not  so  much  by  the  poisons  which 
they  set  free  as  by  something  stored  up  in  the  bodies 
of  the  germs  themselves.  But  if  the  living  germs 
are  put  into  the  body,  they  may  cause  the  disease,  and 
the  very  thing  to  be  guarded  against  might  thus  be 
precipitated. 

So  the  attempt  was  made  to  avoid  this  risk  by  kill- 
ing the  germs  by  heat  and  then  injecting  these  dead 
organisms  beneath  the  skin  of  the  person  to  be  pro- 
tected. This  method  has  been  practiced  on  a  large 
scale  in  some  countries  with  the  typhoid  fever  bacillus 
and  with  the  bacillus  of  the  plague.  While  some  meas- 
ure of  protection  seems  to  have  been  secured  in  this 
way,  the  method  has  not  been  very  generally  adopted. 

There  are  two  other  forms  of  artificially  induced 
immunity  which  we  must  consider  briefly,  since  they 
belong  among  the  greatest  life-saving  agencies  at  our 
command  today.  I  refer  to  vaccination  for  protection 
against  smallpox  and  the  preventive  inoculations  for 
rabies  or  hydrophobia. 

VACCINATION 

First,  vaccination  to  prevent  smallpox.  If  the  good 
Dr.  Jenner,  who  more  than  a  hundred  years  ago  did 
some  excellent  observing  and  some  clear  thinking 
about  what  he  saw,  and  found  out  how  to  prevent 
smallpox,  could  listen  to  our  up-to-date  talk  about  bac- 
teria, microbes,  toxins  and  antitoxins,  and  various 
phases  of  immunity,  he  would  not  understand  a  word 


146  HOUSEHOLD  BACTERIOLOGY 

of  it.  But,  just  the  same,  he  led  the  way  to  the  prac- 
tical banishment  through  artificial  immunity  of  one  of 
the  greatest  and  most  dreaded  scourges  of  man. 

It  was  known  in  Jenner's  time  that  those  who 
milked  cows  having  sores  upon  the  udder,  due  to  a 
local  affection  called  cowpox,  often  acquired  similar 
sores  upon  their  hands.  These  soon  healed,  involving 
only  a  slight  illness.  But  such  persons  had  become 
partially  or  wholly  immune  to  the  more  serious  disease 
of  man,  smallpox. 

Jenner  studied  this  subject  carefully  and  came  to 
the  conclusion  that  artificial  inoculation  with  a  very 
small  portion  of  material  taken  from  such  cattle  might 
be  practiced  on  a  large  scale  with  beneficent  results. 
In  spite  of  much  opposition  he  urged  his  views,  which 
were  gradually  accepted,  until  at  last  the  method  has 
become  almost  universal  in  civilized  communities. 

Large  and  carefully  managed  establishments  are 
now  devoted  to  the  preparation  of  the  virus,  as  it  is 
called,  by  which  artificial  immunity  to  smallpox  is  se- 
cured. The  slight  affection  of  animals — calves — from 
which  the  virus  is  taken  is  called  vaccinia,  while  the 
disease  corresponding  to  it  in  man,  smallpox,  is  called 
variola. 

The  method  now  practiced  on  the  large  scale  is  very 
simple.  Healthy  calves  are  carefully  cleansed  and  kept 
in  clean,  airy  stalls.  The  belly  is  shaved  and  most 
scrupulously  freed  from  all  possible  sources  of  con- 
tamination. Into  this  clean  surface,  slightly  scarified, 


VACCINATION  147 

is  rubbed  some  of  the  virus  secured  from  previous 
cases.  After  a  few  days  this  surface  furnishes  a  yel- 
lowish, watery  material  which  contains  the  protective 
stuff.  This  is  gathered  and  mixed  with  glycerine,  and, 
after  careful  tests  of  its  purity,  is  distributed  to  physi- 
cians in  small  sealed  glass  tubes.  This  virus  rubbed 
on  to  a  scratched  surface  of  the  human  skin  induces 
a  slight  sore,  sometimes  accompanied  by  a  little  ma-- 
laise,  and  then  heals. 

By  this  process  the  liability  to  smallpox  is  very 
greatly  diminished,  but  the  protection  is  reduced  as 
time  passes,  so  that  revaccination  is  necessary  if  the 
fullest  protection  is  to  be  secured. 

It  is  certain  that  smallpox  is  an  infectious  disease 
induced  by  some  form  of  micro-organism.  But  the 
exact  character  of  this  is  still  unknown.  Attempts  to 
cultivate  it  have  thus  far  failed.  It  appears  that  the 
unknown  organism  suffers  diminution  in  virulence  by 
passing  through  the  body  of  the  relatively  insuscepti- 
ble calf,  and  in  this  condition,  while  incapable  of  in- 
citing smallpox  in  man,  is  still  potent  to  establish 
immunity. 

A  good  deal  of  opposition  has  developed  here  and 
there  to  vaccination  even  in  recent  times.  This  has 
been  based  partly  upon  the  fear  lest  foreign  and 
noxious  material  should  be  introduced  into  the  body 
along  with  the  virus.  But  if  it  be  carefully  prepared, 
this  fear  is  groundless.  While  accidents  are  not  im- 
possible, the  ill  effects  which  now  and  then  appear  are 


148  HOUSEHOLD  BACTERIOLOGY 

usually  due  to  the  handling  or  rubbing  of  the  little 
wound  by  dirty  persons,  against  the  warning  of  the 
physician. 

Largely  as  the  result  of  this  form  of  preventive 
inoculation,  smallpox  is  no  longer  to  be  seriously 
dreaded.  In  fact,  in  the  graphic  charts  which  the 
statisticians  make  out  to  show  the  relative  frequency 
of  various  diseases,  the  lines  showing  smallpox  are 
so  short  that  you  can  hardly  see  them ;  while  it  is  those 
representing  tuberculosis,  pneumonia  and  other  dis- 
eases of  the  respiratory  system  which  stretch  in  most 
disquieting  fashion  across  the  page. 

HYDROPHOBIA 

Rabies,  or  hydrophobia,  is  one  of  the  most  dreaded 
of  human  maladies,  and  one  whose  victims  in  former 
times  no  medical  skill  could  save.  It  is  an  infectious 
disease,  though  the  micro-organism  inducing  it  is  still 
undiscovered.  Hydrophobia  is  commonly  acquired  by 
man  through  the  bites  of  rabic  animals,  in  this  country 
most  frequently  the  dog.  The  unknown  infectious 
agent  is  present  in  the  saliva  of  affected  animals.  It 
travels  along  the  nerve  trunks  from  the  site  of  the 
bite  to  the  central  nervous  system,  where  it  especially 
concentrates  itself. 

Pasteur,  the  great  master  in  the  solution  of  knotty 
problems  relating  to  bacteria  and  immunity,  spent 
many  toilsome  and  harassing  years  in  the  study  of 
the  rabic  virus  and  in  attempts  to  devise  an  effective 
method  of  protection.  He  found  at  last  that,  although 
he  could  not  isolate  the  microbe,  he  could  transmit 


HYDROPHOBIA.  149 

the  disease  from  animal  to  animal  by  inoculating  into 
the  nervous  system  of  the  well  animal  a  tiny  portion 
of  nerve  tissue  from  one  which  had  succumbed.  The 
inoculated  animals  invariably  died  at  a  fixed  period. 

After  a  long  series  of  studies  which  we  cannot  here 
review,  he  discovered  that  if  the  spinal  cord  of  one 
of  the  inoculated  animals  (rabbits)  which  had  died 
be  dried  in  a  clean  place,  it  gradually  lost  its  virulence, 
so  that  whereas  at  first  it  invariably  killed  in  seven 
days,  day  by  day  it  lost  its  power,  so  that  after  drying 
for  fourteen  days  it  was  quite  inert.  Given  thus  a 
virus  ranging  gradually  from  the  very  feeble  up  to 
the  strongest,  he  saw  the  possibility  of  gradually  ac- 
customing the  body  to  the  stuff,  so  that  at  last  it  would 
resist  the  very  strongest. 

This  was  tried  on  dogs,  and  it  was  found  that  after 
this  gradual  adaptation  to  the  virus  they  became  at 
last  wholly  indifferent  to  the  bites  of  mad  dogs  or 
the  artificial  inoculation  of  the  strongest  virus.  The 
principle  was  finally  applied  to  man,  with  the  most 
remarkable  and  satisfactory  results. 

Rabies  is  peculiar  in  that  a  long  period  usually 
elapses  between  the  bite  of  a  rabic  animal  and  the 
development  of  symptoms.  This  period,  called  the  in- 
cubation period,  is  in  man  on  the  average  from  thirty 
to  forty  days ;  so  that  if  the  preventive  treatment  be 
instituted  without  undue  delay,  there  is  usually  time 
for  the  adaptation  of  the  subject  to  the  artificial  virus. 
This  accomplished,  the  disease  does  not  occur. 


150  HOUSEHOLD  BACTERIOLOGY 

At  each  laborotary  where  the  treatment  for  the  pre- 
vention of  rabies  is  carried  on,  this  material  of  vary- 
ing degrees  of  potency  is  kept  constantly  ready,  so 
that  as  soon  as  possible  after  a  bite  from  a  supposed 
rabic  animal  the  treatment  may  be  started.  The  oper- 
ation is  a  simple  subcutaneous  injection,  resulting 
usually  only  in  a  slight  or  temporary  local  soreness* 
The  whole  affair  is  completed  within  two  weeks,  when 
all  apprehension  may  be  dismissed.  No  untoward  ef- 
fects follow  the  treatment. 

The  mortality  from  hydrophobia  before  the  day  of 
preventive  inoculation  was  about  16  per  cent.  Through 
this  treatment  it  has  been  reduced  to  about  two-ten.ths 

The  methods  of  securing  artificial  immunity  to  in- 
fectious diseases,  which  we  have  so  hastily  surveyed, 
widely  different  as  the  details  may  be,  all  seem  to 
depend  upon  the  same  wonderful  power  of  the  body 
~ells  to  adapt  themselves  to  harmful  conditions  by  the 
use  to  new  ends  of  the  old  physiological  capacities. 

The  task  of  the  investigator  centers  largely  in  dis- 
covering the  ways  in  which  the  body  cells  may  be 
educated  to  their  new  responsibilities  with  safety  and 
despatch. 

We  seem  to  be  just  at  the  dawn  of  discovery  in  this 
newly  opened  field,  and  the  outlook  is  of  the  highest 
promise  for  the  relief  of  suffering  and  the  prolongation 
of  life. 

The  various  preventive  means  already  devised  are 
in  the  hands  of  experts  and  require  the  greatest  care 


SAFEGUARDS  OF  THE  BODY  151 

on  the  part  of  those  who  make  the  preparations  and 
skill  and  judgment  in  those  who  advise  and  administer 
them.  With  these  things  "the  man  in  the  street"  has 
nothing  to  do.  But  it  is  for  him  to  see  to  it  that  no 
fad  or  ism,  no  false  guides,  nor  ignorance,  nor  indif- 
ference shall  hold  him  from  seeking  and  following 
wise  medical  counsel  in  the  face  of  any  of  the  mala- 
dies from  which  artificial  immunity  may  be  secured 
today.  Here  ignorance  is  folly,  indifference,  crime. 

On  the  other  hand,  it  should  not  be  forgotten  that 
underlying  all  these  protective  measures  is  the  living 
body  machine,  which  each  controls  for  himself.  If, 
through  the  various  phases  of  unwholesome  living  so 
largely  in  evidence  today,  the  machine  is  lacking  in 
vigor,  then  by  so  much  are  the  chances  of  recovery 
lessened  when  the  shadow  of  disease  falls  across  our 
path. 

Not  too  much  work  nor  too  much  play;  not  too 
much  food  and  drink,  but  enough;  good  air  and  in- 
telligent cleanliness  in  houses,  assembly  places  and 
public  conveyances — if  these  conditions  be  fulfilled  in 
such  way  and  measure  as  the  hygiene  and  sanitation 
of  the  day  demand,  we  shall  go  far  to  establish  our 
birthright  to  threescore  years  and  ten.  And  our  im- 
munity to  infectious  disease,  whether  we  brought  it 
into  the  world  with  us,  or  achieve  it  under  the  minis- 
trations of  the  physicians,  will  most  closely  confirm 
the  promise  of  science. 


BIBLIOGRAPHY  153 

BIBLIOGRAPHY 

Bacteria,  Yeasts,  and  Molds  in  the  Home,  by  H   W.  Conn. 

($1.00,  postage  ice  ) 

The  Story  of  Germ  Life,  by  H.  W.  Conn.  (350.,  postage  6c.) 
Dust  and  Its  Dangers,  by  T.  Mitchell  Prudden.  (750.,  postage 

6c) 
The  Story' of  the  Bacteria,  by  T.  Mitchell  Prudden.  (75c., 

postage  6c.) 
Drinking  Water  and  Ice  Supples,  by  T.  Mitchell  Prudden. 

(75c.,  postage  6c.) 
Our  Secret  Friends  and  Foes,  by  Percy  Frankland.  ($1.25, 

postage  i2C.) 

Bacteria,  by  George  Newman.   ($2.00,  postage  i8c.) 
Bacteria  and  Their  Products,  by  G.  S.  Woodhead.  ($1.50, 

postage  i4C.) 
Clean  Milk,  by  S.  D.  Belcher.  ($1.00,  postage  roc.) 

Note:     The  above  books  may  be  borrowed  by  members  of 
the  School  for  the  cost  of  postage. 

For  Advanced  Reading 

A  Laboratory  Guide  in  Elementary  Bacteriology,  by  Wm. 

Dodge  Frost.    ($2.50.) 
Bacteriology  and  the  Public  Health,  by  George  Newman. 

($S-oo.) 

Immunity  in  Infectious  Diseases,  by  Metchnikoff.  ($5.25.) 
Technical  Mycology,  by  Dr.  Franz  Lafar,  2  vols.     ($8.00.) 
Micro-organisms   and   Fermentation,    by  Alfred    Jorgensen. 

($S-oo.) 


1 54  HOUSEHOLD  BA CTERIOLOGY 

Government   Bulletins 

Free  of  the  Department  of  Agriculture,  Washington,  D.  C. 

FARMERS'    BULLETINS 

No.  29  Souring  of  Milk  and  other  Changes  in  Milk  Prod- 
ucts. 

No.    42     Facts  about  Milk  (revised). 

No.  43  Sewage  Disposal  on  the  Farm  and  the  Protection 
of  Drinking  Water. 

No.    57     Butter  Making  on  the  Farm. 

No.     63     Care  of  Milk  on  the  Farm 

No.     73     Experiment  Station  Work  —  IV,  Pure  Water. 

No.  84  Experiment  Station  Work  — VII.  Cured  Test  for 
Clean  Milk. 

No.  92  Experiment  Station  Work  —  IX,  Pasteurization 
in  Butter  Making,  etc. 

No  107  Experiment  Station  Work  —  XIII,  Ropy  Milk  and 
Cream. 

No.  124  Experiment  Station  Work  —  XVII,  Soil  Inocula- 
tion, Distilled  Drinking  Water. 

No.  155     How  Insects  Affect  Health  in  Rural  Districts. 

No.  162  Experiment  Station  Work  —  XXI,  Purifying  Milk 
by  Centrifugal  Separation. 

No.  1 66     Cheese  Making  on  the  Farm. 

No.  175  Home  Manufacture  and  Use  of  Unfermented 
Grape  Juice. 

No.  210  Experiment  Station  Work  —  XXVII,  The  Covered 
Milk  Pail. 

No.  214     Beneficial  Bacteria  for  Leguminous  Crops. 

No.  227     Experiment  Station  Work  —  XXX,  Clean  Milk. 

No.  233     Experiment  Station  Work  —  XXXI,  Cider  Vinegar. 


BIBLIOGRAPHY  155 

No.  240     Inoculation  of  Legumes. 

No.  241     Butter  Making  on  the  Farm. 

No.  262  Experiment  Station  Work  — XXXVI,  Water  for 
Table  Use.  Canning  by  Intermittent  Sterili- 
zation. 

CIRCULARS    OP    BUREAU    OF    ANIMAL    INDUSTRY 

No.       i     Directions  for  Pasteurizing  Milk. 

No.     19     Factory  Cheese  and  How  it  is  Made. 

No.    52     A  Chemical    Examination    of  Various    Tubercle 

Bacilli. 

No.    57     Invisible  Microorganisms. 
No.     70     Tuberculosis  of  Cattle. 
No.    83     Danger  of   Infection    with    Tuberculosis  by   Difr 

ferent  kinds  of  Exposure. 
No.    91     Bacillus  Microphorus  and  its  Economic  Importance. 

REPRINTS  FROM  YEAR  BOOKS 

No.  192     Rabies:     Its   Cause,    Frequency,    and    Treatment 

(1900). 

No.  221     The  Use  and  Abuse  of  Food  Preservatives  (1900). 
No.  262     The  Contamination  of  Public  Water  Supplies,  by 

Algae  (1902). 
Bacteria  and  the  Nitrogen  Problem  (1902). 


SUPPLEMENTAL  PROGRAM  ARRANGED  FOR 
CLASS  STUDY  ON 

HOUSEHOLD  BACTERIOLOGY 

By  S.  Maria  Elliott,  Simmons  College,  Boston 

MEETING  I 

(Study  pages  1-14) 
Dust  and  Dust  Gardens 

The  growth  of  a  dust  garden  will  impress  this  whole  sub- 
ject much  more  vividly  than  any  amount  of  reading.  Each 
member  should  plant  and  watch  the  growth  of  at  least  one 
garden.  One  person  might  prepare  and  sterilize  the  nutrient 
gelatine  for  the  class,  distributing  in  sterilized  wide-mouth 
vials  or  test  tubes  about  two  teaspoonfuls  to  each.  Each 
member  should  sterilize  the  dish  or  dishes,  melt  the  gelatine 
by  placing  the  tube  in  cold  water  and  then  heating  it,  pour 
into  the  Petri  dish,  cover,  cool,  and  plant. 

(If  not  to  be  had  locally,  a  dozen  Petri  dishes  may  be 
obtained  through  the  School  for  $1.90,  a  half  a  dozen  for 
$i .  oo,  not  including  express  charges.  Money  will  be  refunded 
for  those  returned.) 

Arrange  as  varied  conditions  for  experiment  as  possible. 
The  following  list  is  only  suggestive  of  interesting  sources 
and  methods  of  treatment:  • 

(a)  After  sweeping  a  carpeted  room  with  a  dry  broom, 

expose  five  minutes,  keep  at  room  temperature,  but 
not  in  direct  sunlight. 

(b)  Same  as  above  but  kept  in  a  refrigerator. 

(c)  Same  as  "a"  but  shut  up  in  a  box. 

(d)  Dig  out  from  some  corner  of  stairway  or  room  the  dirt 

which  was  overlooked  in  cleaning.  Pulverize  this 
and  scatter  a  little  over  the  jelly.  Keep  in  any 
condition  desired. 

(e)  Let  a  fly  walk  over  the  media. 

157 


158  HOUSEHOLD  BACTERIOLOGY 

(f)  Touch  the  fingers  to  the  jelly  after  handling  dusty  books. 

(g)  Touch  the  jelly  with  pieces  of  money  or  with  a  bill, 
(h)    Take  any  one  of  the  planted  plates.     Lay  over  one-half 

of  the  jelly  a  thick  piece  of  black  paper  or  cloth.     Put 

the  dish  in  direct  sunlight. 
(i)     Scrape  a  bit  of  the  deposit  from  the  teeth  and  touch 

it  to  several  places  on  the  jelly. 
(j)     Rub  a  few  drops  of  boiled  water  in  the  palm  of  the  hand 

and  mix  it  with  the  liquefied  media, 
(k)     Take  one  of  the  dishes  to  a  public  gathering  and  open  it 

for  five  minutes  or  more  when  the  audience  has  been 

seated  for  a  short  time. 

Require  that  each  experimenter  keep  a  daily  record  of 
every  change,  however  minute.  At  the  next  meeting  let 
these  experiments  be  reported,  the  gardens  shown,  and  as 
many  conclusions  drawn  as  may  be  feasible,  leaving  their 
truth  or  falsity  to  be  proved  by  further  study. 

References:  Dust    and    Its    Dangers,    by    T.    M.    Prudden. 

Chapters  I,  II,  III,  IV.     (ysc.,  postage  6c.) 
Our    Secret    Friends    and    Foes,    by   Percy    F. 
Frankland.    Chapters  I -III.     ($i.  25,  postage 

I2C.) 

MEETING  H 

(Study  pages  17-32) 
Character  of  Bacteria 

If  possible,  get  some   physician  to  show  bacteria  under  a 
microscope. 

(a)  Take  some  from  the  dust  gardens  already  planted. 

(b)  Take  a  drop  of  water  from  a  vase  of  flowers  which  has 

stood  unchanged  for  a  week. 
Put  a  wisp  of  hay  in  warm  water,  let  it  stand  for  twenty-four 

hours  in  a  warm  place,  then  examine  with  the  microscope 

a  drop  of  the  brownish  infusion. 
Make  any  experiments  possible  from  "Bacteria,  Yeasts,  and 

Molds,"  by  H.  W.  Conn,  pages  269-285. 


STUDY  PROGRAM  159 

Perhaps  the  physician  may  be  able  to  show  some  pathogenic 
germs. 

References:  The  Story  of  Germ  Life,  by  H.  W.  Conn.  Chap- 
ter I.  (3SC.,  postage  6c.) 

Bacteria,  Yeasts,  and  Molds,  by  H.  W.  Conn. 
Chapters  VIII,  IX.  ($1.00,  postage  loc.) 

The  Story  of  the  Bacteria,  by  T.  M.  Prudden 
Chapters  I,  II,  III,  and  IV.  (75C.,  postage  6c.) 

MEETING  IH 
(Study  pages  33-46) 
Molds  and  Yeasts 

4(a)     Show  a  sample  of   moldy  bread,  cheese,  shoe,  mildew 
from  clothes. 

(b)  Generate  carbon  dioxide  as  shown  on  page  43. 

(c)  Examine  both  yeasts  and  molds  under  microscope  or 

hand  magnifying  glass. 

(d)  Make  a  small  portion  of  "milk  emptins"  as  described 

on  page  6.  Note  changes  which  occur  during  one 
week. 

(e)  Mix  some  bread  dough.      Put  a  part  in  the  ice-chest, 

keep  an  equal  part  at  about  70°  F.  and  a  third  at  a 
much  higher  temperature,  100°  F.  or  over.  Compare 
results  at  the  end  of  six.  twelve,  and  twenty  hours. 

(f)  Pour  boiling  water  on  a  small  bit  of  yeast  cake  and  use 

this  solution  for  mixing  another  portion  of  dough 
which  is  to  be  kept  at  about  70°  F. 

References:  Bacteria,  Yeasts,  and  Molds,  by  H  W.  Conn. 
Chapter  II,  pages  12-24,  and  Chapters  III, 
IV,  V,  and  VI.  ($1.00,  postage  toe.) 

(Select  a  composite  set  of  answers  to  Test  Questions  on  Part 
I  and  send  them  to  the  School  for  correction.  Report  on 
the  supplemental  work  done  and  the  results  of  the  experi- 
ments.) 


160  HOUSEHOLD  BACTERIOLOGY 

MEETING  IV 
(Study  pages  49  —  62) 

Work  of  Bacteria 

Fermentation  and  putrefaction. 

References:  The  Story  of  Germ  Life,  by  H.  W.  Conn.  Chap- 
ters II.  Ill,  IV.  (350.,  postage  6c.) 

Bacteria,  Yeasts,  and  Molds,  by  H.  W.  Conn. 
Chapters  IX-XIIL  ($1.00,  postage  zoc  ) 

Our  Secret  Friends  and  Foes,  by  Percy  F.  Frank- 
land.  Chapters  IV,  V.  ($1.25,  postage  I2C.) 

See  also  U.  S.  Government  Bulletins. 

MEETING  V 

(Study  pages  63-96.) 

Harmful  Dust  Plants 

(a)  Perform  the  experiments  outlined  on  pages  64-66. 

(b)  Boil    a   pint   of   milk    15    minutes.     Pour    into   bottle 

which  has  been  boiled  in  water  the  same  time.    Close 
with  cork  which  has  also  been  boiled. 

Pasteurize  an  equal  portion  (bottle  and  cork  as  above). 
Keep  this  at  about  155°  F.  for  15  minutes.  Keep  both 
under  same  conditions.  Test  each  day  with  blue  litmus 
paper.  Note  first  trace  of  acid.  Test  by  smell  and 
note  first  signs  of  coagulation.  Compare  results  in  time. 
When  opening,  expose  as  little  as  possible  to  dust.  Do 
not  lay  cork  down  or  touch  lower  part  with  fingers.  If 
cork  is  handled  or  exposed  to  more  dust,  boil  again. 
While  cork  is  out,  lay  a  clean  wet  cloth  over  mouth  of 
bottle. 

References:  Dust     and     Its    Dangers,    by    T.    M.    Prudden. 
Chapters  VI,  VII,  VIII.     (750.,  postage   6c.) 
The  Story  of  Germ  Life,  by  H.  W.  Conn.    Chapters 
V,  VI.     (350.,  postage  6c.) 


STUDY  PROGRAM  161 

Bacteria,  Yeasts,   and  Molds,  by  H.  W.  Conn. 

Chapters  XIV,  XV.     ($1.00,  postage  loc.) 
Our   Secret    Friends   and    Foes,   by    Percy    F. 

Frankland,  Chapter  VI.   ($i.  25,  postage  120.) 
The  Story  of   the  Bacteria,  by  T.  M.  Pnidden. 

Chapters  V-XIII.     (750.,  postage  6c.) 

MEETING  VI 

(Study  pages  96  -  1 16) 
Household  Applications 

(a)  Make  out  a  list  on  paper  of  the  most  common  and  most 

harmful  dust  gardens  occurring  in  the  household  — 
the  dishcloth,  refrigerator,  waste-pipe,  damp  floor- 
mop,  or  any  cloths  put  away  in  dark  closets,  uncleaned 
bread  boxes,  etc. 

(b)  Expose  small  portions  of  bread,  cheese,  sauces,  meat, 

milk  to  dusty  air.  Keep  in  warm,  dark  places  and 
note  time,  character,  appearance  of  changes. 

(c)  Consider  the  care  of  hands,  teeth,  all  parts  of  the  body; 

house,  sidewalks,  backyard,  garbage  barrels,  etc.,  from 
•  bacteriological  standpoint. 

References:  Dust    and    Its    Dangers,    by    T.    M.    Prudden. 

Chapters  V,  IX,  XI,  XII.    (750.,  postage  6c.) 

Bacteria,  Yeasts,    and    Molds,  by  H.  W.  Conn. 

Chapter  II,  pages  24-31;  Chapters  VII,  XIV. 

($1.00,  postage  ice.) 

Water    and    Ice,  by  T.     M.     Prudden.    (750., 

postage  6c.) 

(Select  answers  to  Test  Questions  on  Part  II.     Report  on 
supplemental  work  and  experiments.) 


INDEX 


Acetic  acid,  sugar  changed  to, 

61 

Acid,  butyric,  62 
Acids  as  preservatives,   72 
Acquired  immunity,  94,  134 
Agar  for  dust  gardens,  10 
Alcoholic  fermentation,  114 
Alexines,  93 
Animalcules,  109 
Antiseptics,  65 
Antitoxin,  94,  137-144 

diphtheria,  95,  138 
Artificial  immunity,  94,  136 

Bacteria,  16-32 
as  scavengers,  48 
classed  as  plants,  112 
definition  of,  16 
disease  producing,  75 
effect  of  cold  on,  90 
excretions  of,  18 
experiments  with,  64 
food  of,  20 
forms  of,  1 7 
growth  of,  22 
harmful,  63 
in  cheese  making,  60 
in  coarse  meals,  45 
in  "eyes"  of  potato,  45 
in  ice,  85 
in  milk,  14 
in  school  rooms,  107 
liquefying,  74 
method  of  study  of,  112 

163 


natural  home  of,  30 
nitrifying,  51 
on  dust  particles,  97 
secretions  of,  31 
size  of,  23 
structure  of,  17 
useful,  47 
with  flagella,  27 
work  of.  47,  54 
Bacteriology,  history  of,  109- 

"3 

lessons  for  children,   124 
Barriers  of  the  body,  129 
Bed -making,  102 
Blood  poisoning,  91 
Body,  barriers  of  the,  129 
Boiling    clothes,  necessity  for, 

30 
Bread,  baking,  45 

leavened,  6 

Breeding  ground  for  germs,  77 
Brushing  clothing,  106 
Burn  infected  material,  116 
Burning  sweepings,  104 
Butter  bacteria,  55 

bad  flavors  in,  58 

making,  55 
Butyric  acid,  62 

Canned  goods,  70 
Carelessness,  criminal,  83 
Care  of  discharges  in  disease,  79 

of  plumbing,  106 

of  refrigerator,  29 


164 


HOUSEHOLD  BACTERIOLOGY 


Cause  of  lockjaw,  80 
Cheese,  59 

molds  in  ripening,  59 
Cider  vinegar,  60 
Clean  eggs,  73 
Clean  milk,  14 
Cleaning  school  rooms,  107 
Cleanness,  sanitary,  108 
Clothing,  brushing,  106 
Colonies  of  bacteria,  12 

of  dust  plants,   10,  15,  16     . 
Color  of  mold  spores,  38 
Common  methods  of  preserv- 
ing food,  68 

Communicable  diseases,  75 
Compound  microscope,   no 
Compressed  yeast,  43 
Contamination,  sewage,  82 
Covering  food,  104 
Criminal  carelessness,  83 
Crops,  rotation  of,  53 
Cultures,  solid,  in 

Deadly  dish-cloths,  106 
Deaths  from  lockjaw,  80 
Decay,  115 
Diphtheria  antitoxin,   95 

bacillus,  135 
Disinfectants,  65 

nature's,  98 

Disinfectant,  sunshine  as  a,  25 
Disinfect  soiled  articles,  79 
Disease,  care  of  discharges  in, 

79 

from  molds,  36 
germs,  75-86 
germs,  effect  of  light  on,  83 


germs,  identifying,  113 

germs,  origin  of,  77 

nature  of,  131 

producing  bacteria,   132 
Diseases  communicable,    75 

infections,  133 

specific  germs  of,  76 
Drying  food,  70 
Dust,  1-7 

movements  of,  4 

ordinary,  5,  13 

particles,  bacteria  on,  97 

plants,  15 

plants  in  refrigerator    28 

plants,  life  work  of,  63 

sources  of  danger,  114 
Dusters,  washing,  104 
Dust-garden  out  of  doors,   73 

plot,  the,  7 
Dust-gardens,  7-14 

photographs  of,  i,  12,  99, 

'°3.  T°5 

planted   after  sweeping,    98 

soil  for,  13 
Dusting,  rules  for,  104 

time  for,  100 
Dust-proof  room,  2 

Effect  of  antitoxin  on  the  body, 

140 

of  cold  on  bacteria,  90 
of  gastric  juices  on  bacteria, 

87 

of  light  on  disease  germs,  83 
of  poisoning,  92 
of  sunlight  on  disease  germs, 

26 


INDEX 


165 


Eggs,  clean,  73 
Epidemics  of  typhoid,  81 
Essential  oils  as  preservatives, 

72 

Excretions  of  bacteria,  18 
Experiences  of  students,   119- 

124 

Experiments  in  hospitals,  100 
with  bacteria,  64 
with  dust,  7 
with  yeasts,  42 

Extracts    from    the    Instruct- 
or's Note  Book,  117-125 

Favorable  conditions  for 

germs,  76 
Fermentation,  114 

early  theory  of,  no 

processes,  53 

products  of,  115 
Film-forming  bacteria,  22 
Filtered  water,  85 
Filters,  porcelain,  84 
Fission  reproduction,  21 
Flagella,  bacteria  with,  27 
Food,  covering,  104 

of  bacteria,  20 
Forms  of  bacteria,  1 7 
Formation  of  pus,  90 
Fungi,  bacteria  classed  as,  23 

Gas  produced  by  yeast,  44 
Gastric  juices,  effect   on   bac- 
teria, 87 

Germ,  definition  of,  16 
Germs,  breeding  ground  for,  7  7 
disease,  75-86 


pathogenic,  66 
resistance  of  body  to,  86 
Growth  of  bacteria,  22 
of  dust-gardens,  n 
of  mold,  33 
of  yeast,  40 

Harmful  bacteria,  63 

preservatives,  69 
Health,   definition  of,   88 
History  of  bacteriology,  109- 

"3 
Hydrophobia,  148 

Ice,  85 

Identifying  disease  germs,  113 

Immunity,  92,  134 

artificial,  136 

natural,  93 

Importance  of  bacteriology,  3  2 
Infected  material,  burning,  IT  6 
Infection  by  oysters,  82 

method  of,  78 

sources  of,  86 
Infectious  diseases,  133 
Ingredients  of  dust,  4 
Inoculating  the  soil  with  bac- 
teria, 52 

Intermittent  sterilization,    65, 
116 

June  butter,  55 

flavor  bacterium,  56 

Koch's  theory,  in 
Laboratory  study  of  bacteria, 

3i 
Lactic  acid,  production  of,  14 


166 


HOUSEHOLD  BACTERIOLOGY 


Leavened  bread,  6 

Leucocytes,  88 

Life,  spontaneous  gen  station 

of,  109 

work  of  dust  plants,  63 
Liquefying  bacteria,  74 
Lockjaw,  cause  of,  80 

Making  antitoxin,  95 
Meadow  tea,  no 
Metchnikoffs  theory,  93 
Meteoric  dust,  3 
Method  of  infection,  78 

of  study  of  bacteria,  112 
Microbe,  definition  of,  16 
Micro-organisms,  16 
Microscope,  compound,   no 
Mildew,  6,  37 
Milk,  bacteria  in,  14 

clean,  14 

Pasteurized,  67 

souring  of,  13 
Mold,  reproduction  of,  33 

spores,  35 
Molds,  6,  33,  39,  59 

in  ripening  cheese,  59 

work  of,  36 
Moldy  houses,  38 
Movement  of  bacteria,  26 
Movements  of  dust,  4 
Mustiness,  37 

Natural  home  of  bacteria,  30 

immunity,  93 
Nature  of  disease,  131 
Nature's  disinfectants,  96 
Necessity  of  dust,  2 


Newman's  theory,  93 
Nitrifying  bacteria,  51 
Nitrogen  traps,  52 
Nutrient  media  for  dust-gar- 
dens, 13 

Opposition  to  vaccination,  147 
Ordinary  dust,  5,13 
Origin  of  disease  germs,  77 
Oxygen,  relations  of  bacteria 

to,  24 
Oysters,  infection  by,  82 

Pasteur's  theory,  95 
work  of,  in,  148 

Pasteurization,  66,  115 

Pasteurized  milk,  67 

Pathogenic  germs,  66 

Personal  responsibility  for 
sanitation,  108 

Petri  dish,  7 

Phagocytes,  88 

Photograph  of  dust -gardens, 
i,  12,  99,  103,  105 

Planting  dust-gardens,  10 

Plants,  bacteria  classed  as,  112 

Plumbing,  care  of,  106 

Poisoning,  blood,  91 
effects  of,  92 

Polluting  water,  83 

Porcelain  filters,  84 

Precautions  to  avoid  germ  in- 
fection, 79 

Preparing  soil  for  dust-gar- 
dens, 9 

Preservatives,  72 

Preserving  food,  68 


INDEX 


167 


Prevalence  of  dust,  i 
Production  of  lactic  acid,    14 
Products  of  fermentation,  115 

of  yeast  growth,  40 
Protoplasm,  17 
Pus,  formation  of,  90 
Putrefaction,  12 

Rabies,  148 

Refrigerator,  care  of,  29 
Relations  of  bacteria  to  oxy- 
gen, 24 

Removing  dust,  104 
Reproduction  of  bacteria,  20 

of  mold,  33 

Resistance  of  body  to  germs, 
86 

of  spores,  28 
Ripening  cheese,  58 
Roquefort  cheese,  59 
Rotation  of  crops,  53 
Rules  lor  dusting,  104 

Safeguards  of  the  body  against 

disease,  127-151 
Salt  as  a  preservative,  72 
Sanitary  cleanness,  108 
Sanitation,  96-108 

personal  responsibility  for, 

108 

Scavengers,  bacteria  as,  48 
School  rooms,  cleaning,  107 
Secretions  of  bacteria,  31 
Settling  of  bacteria  and  molds, 

98 

Sewage  contamination,  82 
Shape  of  bacteria,  17 


Size  of  bacteria,  23 

of  yeast,  39 

Soil  for  dust-gardens,  8,  13 
Soiled  articles,  disinfect,  79 
Solid  cultures,  1 1 1 
Source  of  dust,  3 
Sources  of  infection,  86 
Souring  of  milk,  13 
Specific  germs  of  diseases,   76 
Spoiling,  71 
Spontaneous  generation  of 

life,  109 
Spores,  116 

mold,  35 

of  bacteria,  27 

of  yeast,  39 

resistance  of,  28 
Starters,  57 
Sterilization,  115 

intermittent,  65,  116 
Structure  of  bacteria,  17 

of  yeast,  39 
Sugar  as  a  preservative,  70 

changed  to  acetic  acid,  61 
Summary,  113 

of  terms,  114 
Sunlight,  effect  on  disease 

germs,  26 

Sunshine  as  a  disinfectant,  25 
Sweeping,  97 

dust -gardens  planted  after, 

98 

Sweepings,  burning,  104 
Symptoms  of  poisoning,  92 

Temperature  for  yeast  growth , 


i68 


HOUSEHOLD  BACTERIOLOGY 


Terms,  summary  of,  114 

Tetanus,  80 

Theories    of    vital    resistance, 

88 

Time  for  dusting,  100 
Toxins,  93 

Typhoid,    epidemic   of,    81 
infection  by  milk,  81 

Useful  bacteria,  47 

Vaccination,  94,  145 
opposition  to,  147 
Vinegar,  60 
Vital  resistance,  theories  of,  87 

Wandering  cells,  88 


Washing  dusters,  104 
Waste  of  nitrogen,  51 
Water,  filtered,  85 

polluting  of,  83 
Work  of  bacteria,  47-54 

of  leucocytes,  88 

of  molds,  36 

of  Pasteur,  1 1 1 

Yeast,  39 

compressed,  44 
generating  carbon  dioxide, 

43 
Yeasts,  effect  of  cold  on,  42 

experiments  with,  42 
Zooglea,  22 


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